Journal of Low Temperature Physics最新文献

{"title":"Visualizing the Odd-Parity Superconducting Order Parameter and Its Quasiparticle Surface Band in UTe2","authors":"Shuqiu Wang,&nbsp;J. C. Séamus Davis","doi":"10.1007/s10909-026-03384-w","DOIUrl":"10.1007/s10909-026-03384-w","url":null,"abstract":"<div><p>A distinctive identifier of nodal intrinsic topological superconductivity (ITS) would the appearance of an Andreev bound state on crystal surfaces parallel to the nodal axis, in the form of a topological quasiparticle surface band (QSB) appearing only for <span>(T &lt; T_{C})</span>. Moreover, the theory shows that specific QSB characteristics observable in tunneling to an <i>s</i>-wave superconductor can distinguish between chiral and non-chiral ITS order parameter <span>(Delta_{{varvec{k}}})</span>. To search for such phenomena in UTe₂, <i>s</i>-wave superconductive scan-tip scanning tunneling microscopy (STM) imaging was employed. It reveals an intense zero-energy Andreev conductance maximum at the UTe₂ (0–11) crystal termination. The development of the zero-energy Andreev conductance peak into two finite-energy particle-hole symmetric conductance maxima as the tunnel barrier is reduced and then signifies that UTe₂ superconductivity is non-chiral. Quasiparticle interference imaging (QPI) for an ITS material should be dominated by the QSB for energies within the superconductive energy gap <span>(left| E right| le {Delta })</span>, so that bulk <span>(Delta_{{varvec{k}}})</span> characteristics of the ITS can only be detected excursively. Again using a superconducting scan-tip, the in-gap quasiparticle interference patterns of the QSB of UTe₂ were visualized. Specifically, a band of Bogoliubov quasiparticles appears as a characteristic sextet <span>({varvec{q}}_{i} :i = 1 - 6{ })</span> of interference wavevectors, showing that QSB dispersions <span>(varvec{k})</span>(<i>E</i>) occur only for energies <span>(left| E right| le Delta_{max })</span> and only within the range of Fermi momenta projected onto the (0–11) crystal surface. In combination, these phenomena are consistent with a bulk <span>(Delta_{{varvec{k}}})</span> exhibiting spin-triplet, time-reversal conserving, odd-parity, <i>a</i>-axis nodal, <i>B</i>_<i>3u</i> symmetry in UTe₂.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03384-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical Investigations of Tetrameric Magnetic Molecules for Sub-kelvin Cooling","authors":"Dennis Westerbeck,&nbsp;Jürgen Schnack","doi":"10.1007/s10909-026-03391-x","DOIUrl":"10.1007/s10909-026-03391-x","url":null,"abstract":"<div><p>Magnetic molecules are a class of compounds that is also investigated in view of their magnetocaloric properties. The isothermal entropy change and the adiabatic temperature change are key figures of merit for magnetocaloric performance. Here, we investigate spin systems of realistic molecular structures comprising four spins. In view of potentially large spin quantum numbers as for gadolinium, we model these spin systems by a combination of Heisenberg and dipolar spin-spin interactions. It turns out that a tetrahedral structure with ferromagnetic exchange interactions yields the best figures of merit.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03391-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147363082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scanning Tunneling Spectroscopy of Superconducting Nitridized Aluminum Thin Films","authors":"Jose Antonio Moreno,&nbsp;Pablo García Talavera,&nbsp;Alba Torras-Coloma,&nbsp;Gemma Rius,&nbsp;P. Forn-Díaz,&nbsp;Edwin Herrera,&nbsp;Isabel Guillamón,&nbsp;Hermann Suderow","doi":"10.1007/s10909-026-03390-y","DOIUrl":"10.1007/s10909-026-03390-y","url":null,"abstract":"<div><p>Nitride-based superconductors represent a family of superconducting thin film materials displaying higher quality than their corresponding bare superconductor when used in devices for applications such as cosmic radiation sensing. In recent times, niobium-based and titanium-based nitrides were used to improve the quality of superconducting devices in quantum technology applications. Recently, nitridized aluminum (NitrAl) has been found to display higher critical temperatures and enhanced resilience to magnetic fields compared to those of Al, making it a new interesting candidate for superconducting quantum circuit applications. However, the microscopic properties of NitrAl remain highly unexplored. Here, we use scanning tunneling microscope (STM) to measure the superconducting density of states of a thin film sample of nitridized aluminum (NitrAl), with a room temperature resistivity between pure Al and fully insulating aluminum nitride. We show that the in-gap density of states is zero up to about <span>(hbar omega =250~mathrm {mu eV})</span> and that there is a distribution of values of the superconducting gap around <span>(Delta _0=360~mathrm {mu eV})</span>, close to the BCS expectation <span>(Delta =1.76 k_{textrm{B}}T_{textrm{c}})</span>. We also find varying superconducting gap values at the nanometer scale, by approximately 10%, when probing different regions of the sample. These results suggest a gap which is larger than the one of pure Al and is spatially more homogeneous than the superconducting gap values often found in thin films. Our work demonstrates that STM is as a powerful tool to screen materials for quantum devices through the measurement of the spatial dependence of the superconducting density of states.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03390-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single Crystal Growth and Pressure Effect on Superconductivity of (hbox {FeSe}_{mathrm{1-x}} hbox {S}_{textrm{x}})","authors":"Kiyotaka Miyoshi,&nbsp;Yumi Yamamoto,&nbsp;Takanobu Nakatani,&nbsp;Daichi Izuhara,&nbsp;Ikumi Matsushima","doi":"10.1007/s10909-026-03385-9","DOIUrl":"10.1007/s10909-026-03385-9","url":null,"abstract":"<div><p><span>(hbox {FeSe}_{mathrm{1-x}} hbox {S}_{textrm{x}})</span> is known to have a characteristic phase diagram where superconducting (SC), nematic and antiferromagnetic (AFM) phases coexist or compete to each other. We report single crystal growth of <span>(hbox {FeSe}_{mathrm{1-x}} hbox {S}_{textrm{x}})</span> and pressure effect on superconductivity for the specimens with <i>x</i>=0.02 through the measurements of DC magnetization (<i>M</i>) and electrical resistivity (<span>(rho)</span>) as a function of temperature (<i>T</i>). Single crystals of <span>(hbox {FeSe}_{mathrm{1-x}} hbox {S}_{textrm{x}})</span> (<span>(xle 0.17)</span>) with a maximum dimension of 1.5<span>(times)</span>1.5 <span>(hbox {mm}^2)</span> were successfully obtained by a chemical vapor transport method. The <i>M</i>(<i>T</i>) and <span>(rho)</span>(<i>T</i>) measurements have revealed that a nematic phase is suppressed and disappears at <span>(sim)</span>1.5 GPa, where superconducting transition temperature <span>(T_{textrm{c}})</span> shows a local minimum, while AFM phases appear separately inside and outside the nematic phase. A crossover of superconductivity near the end point of AFM phase reported in our previous study for <span>(xge 0.04)</span> was not observed for <i>x</i>=0.02.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03385-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147336219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tuning Cavity Modes in BSCCO Terahertz Emitters via Geometric Design","authors":"Huili Zhang,&nbsp;Wanghao Tian","doi":"10.1007/s10909-026-03382-y","DOIUrl":"10.1007/s10909-026-03382-y","url":null,"abstract":"<div><p>This study investigates the influence of cavity mode resonance on coherent terahertz emission in intrinsic Josephson junction stacks of the high-temperature superconductor Bi₂Sr₂CaCu₂O_8+x (BSCCO). Two BSCCO samples with deliberately varied geometries are designed to decouple the role of geometric dimensions from material parameters, enabling a systematic exploration of the correlation between terahertz emission and cavity modes. Experimental results reveal that in the low-bias regime, discrete emission frequencies exclusively align with longitudinal (0, m) cavity modes, whose selection is primarily governed by the stack’s length. Each resonant mode corresponds to a distinct sharp peak in the emitted power. In contrast, the high-bias regime enables continuous frequency tuning though emission is significantly affected by hotspot formation. Notably, the transverse (1, 0) mode, when excited, exhibits significantly weaker radiation power compared to the longitudinal modes, highlighting the critical impact of geometry on radiation efficiency. This work highlights geometric design as a highly effective and tunable strategy for controlling terahertz emission in BSCCO stacks, offering experimental insights for optimizing high-<i>T</i>_c superconductor terahertz sources.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147341423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geometric Control of Narrow-gap Heat Switches","authors":"Maros Skyba,&nbsp;Kejian Jiang,&nbsp;Yulong He,&nbsp;Xiaoyue Tan,&nbsp;Peng Xu","doi":"10.1007/s10909-026-03381-z","DOIUrl":"10.1007/s10909-026-03381-z","url":null,"abstract":"<div><p>This work investigates the influence of geometrical configuration and mechanical contact efficiency on the thermal performance of cryogenic heat switches. A simulation framework was developed to model heat transfer across copper stainless-steel assemblies, incorporating thermal contraction, enthalpy evolution, and thermal contact resistance representing the quality of surface contact between the conductors. The results show that both the conductor length ratio and thermal contact resistance strongly affect the disconnection temperature. When the thermal contact resistance approaches unity, the switch behaviour becomes largely independent of geometry, whereas high thermal contact resistance values amplify the effect of conductor ratio and mechanical misalignment. Experimental tests performed on prototype switches confirmed these trends qualitatively, revealing a pronounced temperature lag between the hot and cold ends, consistent with reduced interfacial conductivity. The introduction of a negative gap was found to further lower the disconnection temperature in all cases. Based on these findings, design improvements such as implementing a conical interface are proposed to enhance alignment, increase reduce the thermal contact resistance, and achieve more reproducible switching characteristics.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147341719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-Impurity-Induced Localization Transitions in Electronic Systems","authors":"Niaz Ali Khan,&nbsp;Munsif Jan,&nbsp;Muzamil Shah,&nbsp;Muhammad Sajid,&nbsp;Muhammad Mateen,&nbsp;Mushtaq Ali","doi":"10.1007/s10909-026-03387-7","DOIUrl":"10.1007/s10909-026-03387-7","url":null,"abstract":"<div><p>Anderson localization is a fundamental phenomenon in disordered quantum systems, where transport is suppressed by wave interference from extensive randomness. Moving beyond traditional multi-impurity scenarios, we investigate impurity-induced localization phenomena in low-dimensional tight-binding systems by focusing on the properties of impurity-generated bound states. By introducing a single on-site impurity into an otherwise extended lattice, we demonstrate that the impurity can host a bound state whose spatial character undergoes a transition from extended to localized as the impurity strength surpasses a critical value. This transition pertains solely to the impurity state, while the bulk states of the host system remain extended. We characterize the localization behavior by analyzing two distinct spatial profiles of the bound states: one with symmetric decay and another with exponential decay from the impurity site. Our results highlight how a local perturbation can induce nontrivial localization behavior at the level of individual eigenstates, without implying a global localization transition of the underlying electronic system.\u0000</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147340957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Commissioning Results of Cryogenic Helium Plant for Korean Heavy Ion Accelerator After a Three-Year Overhaul","authors":"Junghyun Yoo,&nbsp;Jinwook Kim,&nbsp;Inmyung Park,&nbsp;Hyun Chul Jo,&nbsp;Min Ki Lee,&nbsp;Seojeong Kim,&nbsp;Gyuho Lee,&nbsp;Jaehak Han,&nbsp;Yeonsei Chung,&nbsp;Jae Hee Shin","doi":"10.1007/s10909-026-03389-5","DOIUrl":"10.1007/s10909-026-03389-5","url":null,"abstract":"<div><p>The Institute for Rare Isotope Science (IRIS) has two large-scale cryogenic helium plants (hereinafter referred to as”cryoplant”) for the Korean heavy ion accelerator. Each cryoplant is designed to perform 2.05 K operation of the superconducting linear accelerator (SCL). This paper focuses on the smaller unit, the SCL3 cryoplant, which provides simultaneous cooling capacity of 10,250 W at 45 K, 1040 W at 4.5 K and 910 W at 2.05 K. The SCL3 cryoplant was handed over from the manufacturer in August 2022, and has been operated by IRIS since then. A major overhaul was suggested over a three-year interval in preparation for long-term continuous operation so we executed the overhaul from October 2024 to March 2025. The overhaul included the replacement of consumable parts in the warm compressors and 2.05 K warm pumps as well as renewal of coalescing filters and activated carbon to eliminate residual oil from the compressed helium stream. On the coldbox side, critical filters such at the coldbox inlet and the turbine gas bearing inlet were also inspected. After the overhaul, a single refrigeration commissioning test was conducted to validate the mechanical integrity and operational performance. While several minor issues were identified during the test, the system demonstrated acceptable stability. This paper presents the commissioning procedure, observed minor problems, and evaluation of system performance, along with a brief overview of the overhaul activities.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-026-03389-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147340527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Analysis of Displacement Characteristics and Surface Deformation of Anisotropic Superconductor","authors":"Yufeng Zhao,&nbsp;Qingwen Pei,&nbsp;Xinyu He","doi":"10.1007/s10909-026-03386-8","DOIUrl":"10.1007/s10909-026-03386-8","url":null,"abstract":"<div><p>In this paper, we employ the Ginzburg–Landau theory alongside classical anisotropic elasticity mechanics to develop a coupled force–magnetic–elastic model. We describe the surface deformation of YBa₂Cu₃O_7−δ (YBCO) superconductors under the influence of a magnetic field, as well as the impact of the anisotropy ratio on this surface deformation. Our calculations reveal the surface dipole potential and deformation displacement of YBCO in the vortex state. Notably, we find a positive correlation between vortex density and surface displacement with variations in the magnetic field. Furthermore, the amplitudes of surface deformation and displacement are significantly influenced by the anisotropy ratio. This study elucidates the predominant role of the surface dipole potential in driving deformation, thereby providing a theoretical foundation for understanding the electromagnetic–elastic coupling mechanism in anisotropic superconductors. Additionally, it serves as a significant reference for the micro- and nanomechanical design of superconducting devices.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147339999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fermi Liquid Theory for Spin Current Dynamics of a Ferromagnet","authors":"Chen Sun,&nbsp;Wayne Saslow","doi":"10.1007/s10909-025-03357-5","DOIUrl":"10.1007/s10909-025-03357-5","url":null,"abstract":"<div><p>Theoretical understanding of spin dynamics in ferromagnets is a crucial question in spintronics. A recent work considered the dynamical equations for ferromagnets using Onsager’s irreversible thermodynamics with fundamental variables magnetization <span>(vec {M})</span> and spin current <span>(vec {J}_{i})</span>. The resulting equations have the same structure as Leggett’s Fermi liquid theory for the nuclear paramagnet <span>(^{3})</span>He. Specifically, <span>(partial _{t}vec {J}_{i})</span> contains a term varying as <span>(partial _{i}vec {M})</span> that we interpret as associated with a vector spin pressure and a term giving a mean-field along <span>(vec {M})</span>, about which <span>(vec {J}_{i})</span> precesses. (There is also a decay term in <span>(partial _{t}vec {M})</span> not normally present in the Leggett equations, which are intended for shorter-time spin-echo experiments.) The present work applies Fermi liquid theory to <span>(vec {J}_{i})</span> of ferromagnets. The resulting dynamical equation for <span>(vec {J}_i)</span> confirms the form of <span>(vec {J}_i)</span> found earlier using irreversible thermodynamics, but now the previously unknown exchange constant is given in terms of the quasiparticle interaction parameters of Fermi liquid theory. Our results indicate that study of spin currents in ferromagnets can yield information about the Fermi liquid coefficients.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"222 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2026-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147339239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}