Materials Today Quantum最新文献

{"title":"Quantum geometry driven finite-momentum exciton fluctuations in flat-band systems","authors":"Yi-Chun Hung,&nbsp;Xiaoting Zhou,&nbsp;Arun Bansil","doi":"10.1016/j.mtquan.2026.100076","DOIUrl":"10.1016/j.mtquan.2026.100076","url":null,"abstract":"<div><div>Quantum geometry is instrumental in stabilizing exotic phenomena in systems ranging from topological insulators to superconductors. In dispersionless flat bands, where the kinetic energy is quenched, the quantum metric emerges as the fundamental driver of macroscopic collective phenomena. Here, we theoretically demonstrate that lattice-geometry-induced flat bands, such as those in kagome and Lieb lattices, provide a fertile platform for realizing a quantum-geometry-driven excitonic insulator (EI) phase. By applying an out-of-plane Zeeman field to lift spin degeneracy without spin–orbit coupling, we establish a Ginzburg–Landau framework in which the electron–hole wavefunction-overlap directly maps the flat-band quantum metric onto the macroscopic free energy. This mapping plays a key role in both the EI and the associated superfluid phases, with the coherence length and phase stiffness emerging directly from the quantum metric. Our analysis reveals that under strong interactions, the quantum metric reverses the sign of the kinetic coefficient of the amplitude mode. Rather than destabilizing the uniform condensate, this enhances the amplitude fluctuations at a finite momentum, giving rise to a finite-momentum superfluid density fluctuation (FMSDF) regime. A qualitative signature of the FMSDF regime is shown to be an enhanced finite-momentum susceptibility of the in-plane magnetization amplitude. Our findings establish a rigorous link between the flat-band quantum geometry and dynamic collective excitonic states, and suggest covalent-organic frameworks (COFs) as promising candidates for materials realization.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"11 ","pages":"Article 100076"},"PeriodicalIF":0.0,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148935053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disorder-driven Weyl-Kondo semimetal phase in WTe2","authors":"Arpan Manna,&nbsp;Sunit Das,&nbsp;Amit Agarwal,&nbsp;Soumik Mukhopadhyay","doi":"10.1016/j.mtquan.2026.100070","DOIUrl":"10.1016/j.mtquan.2026.100070","url":null,"abstract":"<div><div>In this Letter, we report the observation of disorder-driven anisotropic Kondo-like screening and spontaneous Hall effect in bulk WTe₂, a nonmagnetic type-II Weyl semimetal. We show that Kondo-like scattering emerges more prominently in disordered samples and produces a magnetoresistive correction that is strongly anisotropic with respect to both current and magnetic field orientation, consistent with the underlying type-II Weyl dispersion. Strikingly, we find a spontaneous Hall effect in zero magnetic field, whose magnitude is enhanced with disorder, together with a large second-harmonic Hall signal exhibiting quadratic current scaling. We argue that Berry curvature–driven nonequilibrium transport, with the disorder-driven Kondo-like interaction pinning the Fermi level near the Weyl nodes, could possibly account for both the second-order and spontaneous Hall responses. These findings suggest the possibility of disorder acting as an effective control knob for inducing correlated topological phases in weakly correlated Weyl semimetals.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"10 ","pages":"Article 100070"},"PeriodicalIF":0.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148184428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variational methods for simulating the quantum dynamics of Ising spin chains","authors":"Mohamed Barhoumi,&nbsp;Milad Ghadimi,&nbsp;Muhammad Idham Habibie,&nbsp;Riccardo Bassoli,&nbsp;Frank H.P. Fitzek","doi":"10.1016/j.mtquan.2026.100073","DOIUrl":"10.1016/j.mtquan.2026.100073","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Variational quantum time evolution is a fundamental issue in physics and engineering. It provides a strong framework for modeling the dynamics of quantum states, which is essential for efficiently running quantum networks. It presents an excellent toolkit that can improve the efficacy, reliability, resilience and performance of quantum networks, opening the door to more sophisticated distributed computer systems, quantum communication, and other quantum technologies. The imaginary time evolution of quantum systems is one useful tool that enables the generation of ground or thermal states. In this work, we address standard variational principles, such as the Dirac and Frenkel variational principles, the McLachlan variational principle and the time-dependent variational principle to model real-time dynamics, as well as the Rayleigh–Ritz approach to address static challenges. We also present the variational quantum time evolution VarQITE and VarQRTE formalism in the density matrix method, which is not influenced by the global phase of the quantum state. We calculate the ground-state energy of our quantum Ising spin chain, using VarQITE with different interaction energies &lt;span&gt;&lt;math&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, where three cases are considered. In the non-interacting (&lt;em&gt;NI&lt;/em&gt;) case (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), we show that the energy of the ground state accomplished with VarQITE converges to an energy of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;00&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; Hartree at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; seconds. In the Ferromagnetic (&lt;em&gt;FM&lt;/em&gt;) interaction case (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;), four scenarios are used to obtain the energy of the Hamiltonian. We show that the convergence and the energy &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;mi&gt;H&lt;/mi&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; are sensitive to the energy of interaction &lt;span&gt;&lt;math&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;. Furthermore, the influence of the negative values of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, which correspond to the antiferromagnetic (&lt;em&gt;AFM&lt;/em&gt;) case, on the energy of the ground state is also studied. We find that VarQITE and the exact classical solution are matched. We also investigated the expectation values for magnetization &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, employing VarQRTE and the exact classical solution. The NI, FM, and AFM cases are accomplished here. We find that when the spins are not interacting, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;〈&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;〉&lt;/mo&gt;&lt;/mrow&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, while it oscillates over time &lt;span&gt;&lt;math&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; when &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;J&lt;/mi&gt;&lt;mo&gt;&gt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"10 ","pages":"Article 100073"},"PeriodicalIF":0.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148523680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Targeted production of interstitial color centers in 2D materials: Machine-learning accelerated ion impact simulations","authors":"Silvan Kretschmer,&nbsp;Joel Davidsson,&nbsp;Kristian S. Thygesen","doi":"10.1016/j.mtquan.2026.100071","DOIUrl":"10.1016/j.mtquan.2026.100071","url":null,"abstract":"<div><div>Color centers in 2D materials show promise for quantum technologies and are gaining rapid interest. Mainly, vacancies and substitutional clusters are considered, with interstitial defects being largely unexplored. By searching through the imp2D database, we identified stable interstitial defects with magnetic multiplet states. While the workflow applied here can be generalized to the full set of interstitial defects, we chose to characterize the Os interstitial in <figure><img></figure> in detail, calculating its photoluminescence spectrum and zero field spitting — relevant quantities especially for quantum applications. As calculations for the Os interstitial yielded promising results, extensive ion impact simulations using machine-learning interatomic potentials were carried out. Our results not only highlight the importance of interstitial color centers in 2D materials for quantum technologies but also demonstrate possible fabrication routes and encourage their experimental realization using low-energy ion implantation.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"10 ","pages":"Article 100071"},"PeriodicalIF":0.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148523681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum spin-interference–driven giant and oscillatory junction magnetoresistance in spin-gapless Mn₂CoAl/SiO₂/p-Si heterostructures","authors":"Subham Mohanty,&nbsp;Garima Yadav,&nbsp;Nilay Maji","doi":"10.1016/j.mtquan.2026.100072","DOIUrl":"10.1016/j.mtquan.2026.100072","url":null,"abstract":"<div><div>Spin-selective transport across ferromagnet/semiconductor interfaces is central to semiconductor spintronics but remains challenging due to conductivity mismatch and interfacial spin depolarization. Here we demonstrate robust spin-dependent transport and giant junction magnetoresistance (JMR) in sputter-deposited Mn₂CoAl/SiO₂/<em>p</em>-Si heterostructures fabricated using a CMOS-compatible process. Highly ordered inverse-Heusler Mn₂CoAl (MCA) thin films exhibiting near-ideal XA chemical ordering (S ≈ 0.94) and a Curie temperature of ∼590 K were successfully synthesized using magnetron sputtering. The spin-gapless semiconducting nature of Mn₂CoAl is experimentally supported by a weakly temperature-dependent resistivity with a very small negative temperature coefficient of resistance (TCR ≈ - 4.2 × 10⁻⁹ Ω·m·K⁻¹) and a nonsaturating linear magnetoresistance over a wide range of magnetic fields and temperatures. A giant positive JMR of ∼825% at 10 K and ∼134% at room temperature is observed despite the presence of only a single ferromagnetic electrode. Systematic variation of the SiO₂ tunnel barrier thickness reveals a reproducible oscillatory sign reversal of the JMR accompanied by an exponential decay in magnitude. Analysis of the oscillation period indicates that the effect is mediated by a confined two-dimensional carrier layer near the Si/SiO₂ interface. These results suggest that spin-polarized carriers tunnel through the oxide barrier via phase-coherent spin-dependent tunneling, where thickness-dependent quantum phase accumulation modulates the tunneling conductance. These findings provide a scalable route toward silicon-compatible spin filters, magnetic sensors, and phase-engineered spintronic devices.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"10 ","pages":"Article 100072"},"PeriodicalIF":0.0,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148241066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum correlation and synchronisation-enhanced energy transfer in driven-dissipative light-harvesting dimers","authors":"Wenhao Xu (徐文昊)","doi":"10.1016/j.mtquan.2026.100059","DOIUrl":"10.1016/j.mtquan.2026.100059","url":null,"abstract":"<div><div>Quantum synchronisation has recently been proposed as a mechanism for electronic excitation energy transfer in light-harvesting complexes, yet its robustness in driven-dissipative settings remains under active investigation. Here, we revisit this mechanism in cryptophyte photosynthetic antennae using an exciton–vibrational dimer model. By comparing the full open quantum dynamics with semi-classical rate equations for electronic density-matrix elements and vibrational observables, we demonstrate that quantum correlations between electronic and vibrational degrees of freedom, beyond the semi-classical factorised limit, underpin the emergence of quantum synchronisation. Furthermore, we introduce an environment-assisted transfer mechanism arising as a nonlinear, non-Condon correction to the dipole–dipole interaction. This mechanism enables long-lived quantum coherence and continuous, synchronisation-enhanced energy transfer in a driven-dissipative regime, thereby suggesting new avenues for investigating photosynthetic energy-transfer dynamics.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"9 ","pages":"Article 100059"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular insights into balanced hole and electron transport in urea-modified fluorene for OLED applications","authors":"G.S. Gopika Krishnan,&nbsp;K. Muraleedharan","doi":"10.1016/j.mtquan.2026.100060","DOIUrl":"10.1016/j.mtquan.2026.100060","url":null,"abstract":"<div><div>The optoelectronic and charge-transport characteristics of fluorene (F) and its urea derivative, N-(9H-fluoren-9-yl) urea (9FU), are investigated in this work using DFT and TD-DFT. Electronic excitations, charge extraction parameters, ionisation potentials, electron affinities, and reorganisation energies were all methodically examined. The findings demonstrate that urea substitution at fluorene's 9-position increases charge-transfer balance and electron magnetism, allowing for ambipolar behaviour. 9FU has better charge-transport and excitation properties than fluorene, suggesting that it could be used in effective OLED applications.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"9 ","pages":"Article 100060"},"PeriodicalIF":0.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interface controlled Berry phase and anisotropic spin–charge conversion in altermagnet–topological insulator bilayers","authors":"Juhi Singh,&nbsp;Narayan Mohanta","doi":"10.1016/j.mtquan.2025.100058","DOIUrl":"10.1016/j.mtquan.2025.100058","url":null,"abstract":"<div><div>We propose an altermagnet–topological insulator bilayer as a platform to engineer Berry phase driven spin–charge responses using an interfacial buffer layer. Using a momentum-space lattice model and linear-response theory, we investigate a <span><math><mi>d</mi></math></span>-wave altermagnet coupled to a topological insulator and highlight the crucial role of spin-flip tunneling in shaping its electronic and transport properties. Interfacial hybridization strongly modifies the band structure, leading to anisotropic Rashba–Edelstein and Hall responses. The spin-flip component of the coupling induces an inverse <span><math><mi>d</mi></math></span>-wave spin texture in the altermagnetic bands, signaling the onset of an altermagnetic topological phase. This coupling also renders the Rashba–Edelstein effect strongly in-plane anisotropic, enhancing the transverse response relative to ferromagnetic or antiferromagnetic analogues. These results establish interfacial spin-flip tunneling as a practical control knob for direction-sensitive, stray-field–free spin–charge conversion in correlated topological heterostructures.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"8 ","pages":"Article 100058"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145684135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diagnosis of enforced phonon band crossings in the entire frequency window by compatibility relations","authors":"Houhao Wang ,&nbsp;Sergey Y. Savrasov ,&nbsp;Xiangang Wan ,&nbsp;Feng Tang","doi":"10.1016/j.mtquan.2025.100056","DOIUrl":"10.1016/j.mtquan.2025.100056","url":null,"abstract":"<div><div>Topological band crossings (BCs) such as Dirac and Weyl points can provide intriguing physical properties in both fermionic systems and bosonic systems, like surface Fermi arcs, chiral anomaly, spin-momentum locking, and among others. Unlike BCs at high-symmetry points (HSPs) formed by a single degenerate irreducible representation (irrep), those in high-symmetry lines (HSLs) are degeneracies formed by two different irreps. For fermionic systems, such BCs near the Fermi level can be effectively diagnosed using symmetry data at HSPs, namely, the number of times each irrep of occupied bands occurs at HSPs. For phonon systems, phonon BCs in the entire frequency window are meaningful. Here, we propose a new diagnostic scheme for detecting phonon BCs by compatibility relations (CRs), which would otherwise be invisible to traditional methods as applied in electronic bands. Based on 230 space groups, we apply our diagnostic scheme to the Phonon Database at Kyoto University (consisting of 10,034 materials) and identify 2,815,357 emergent particles (EMPs) in HSLs. These EMPs include C-1 WP, C-2 DP, C-2 WP, C-3 WP, DP, P-WNL, P-WNLs, QDP, QTP, and TP, providing a platform to assist experimentalists in exploring the practical application value of phonon EMPs. Our diagnostic scheme can also be applied to other bosonic systems like photon and magnon systems and extended to other symmetries, such as magnetic space groups and spin space groups.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"8 ","pages":"Article 100056"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145364168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear bulk photocurrent probe Z2 topological phase transition in noncentrosymmetric materials","authors":"Debasis Dutta ,&nbsp;Raihan Ahammed ,&nbsp;Yingdong Wei ,&nbsp;Xiaokai Pan ,&nbsp;Xiaoshuang Chen ,&nbsp;Lin Wang ,&nbsp;Amit Agarwal","doi":"10.1016/j.mtquan.2025.100052","DOIUrl":"10.1016/j.mtquan.2025.100052","url":null,"abstract":"<div><div>Detecting topological phase transitions in bulk is challenging due to the limitations of surface-sensitive probes like ARPES. Here, we demonstrate that nonlinear bulk photocurrents, specifically shift and injection currents, serve as effective probes of <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> topological transitions in noncentrosymmetric materials. These photocurrents show a robust polarity reversal across the <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> phase transition, offering a direct optical signature that distinguishes strong topological phases from weak or trivial ones. This effect originates from a reorganization of key band geometric quantities, the Berry curvature and shift vector, on time-reversal-invariant momentum planes. Using a low-energy Dirac model, we trace this behavior to a band inversion in the time-reversal-invariant momentum plane that drives the topological transition. We validate these findings through tight-binding model for Bi<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>Te<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> and first-principles calculations for ZrTe<span><math><msub><mrow></mrow><mrow><mn>5</mn></mrow></msub></math></span> and BiTeI, where the topological phase can be tuned by pressure or temperature. Our results establish nonlinear photocurrent as a sensitive and broadly applicable alternative probe of <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> topological phase transitions.</div></div>","PeriodicalId":100894,"journal":{"name":"Materials Today Quantum","volume":"8 ","pages":"Article 100052"},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}