K. Sriram, Yaswanth Sai Pappu, M. S. Devapriya, Jhantu Pradhan, Arabinda Haldar, Chandrasekhar Murapaka
{"title":"Deposition Pressure Dependence on Spin Hall Angle of W Thin Films Grown on NiFe","authors":"K. Sriram, Yaswanth Sai Pappu, M. S. Devapriya, Jhantu Pradhan, Arabinda Haldar, Chandrasekhar Murapaka","doi":"10.1142/s2010324723400271","DOIUrl":null,"url":null,"abstract":"<p>Spin-to-charge conversion and vice versa due to spin-orbit coupling in ferromagnet-heavy metal heterostructure is of paramount interest for developing energy-efficient spintronic devices. Here, we have systematically investigated the effect of Ar deposition pressure (<span><math altimg=\"eq-00001.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>P</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">Ar</mtext></mstyle></mrow></msub><mo stretchy=\"false\">)</mo></math></span><span></span> on the tungsten (<i>W</i>) crystalline phase and extracted spin-dependent transport parameters. X-ray diffraction results show that 10<span><math altimg=\"eq-00002.gif\" display=\"inline\" overflow=\"scroll\"><mspace width=\".17em\"></mspace></math></span><span></span>nm-thick <i>W</i> films exhibit a structural phase transition from a mixed phase of <span><math altimg=\"eq-00003.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><mi>α</mi><mo>+</mo><mi>β</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-<i>W</i> to a single phase of <span><math altimg=\"eq-00004.gif\" display=\"inline\" overflow=\"scroll\"><mi>β</mi></math></span><span></span>-<i>W</i> as a function of <span><math altimg=\"eq-00005.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>P</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">Ar</mtext></mstyle></mrow></msub></math></span><span></span>. The observed phase transition is due to a decrease in adatom’s energy and surface mobility. Interestingly, only the <span><math altimg=\"eq-00006.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><mi>α</mi><mo>+</mo><mi>β</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-<i>W</i> phase is found to stabilize when <i>W</i> sputtered on a seed Ni<span><math altimg=\"eq-00007.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow></mrow><mrow><mn>8</mn><mn>0</mn></mrow></msub></math></span><span></span>Fe<span><math altimg=\"eq-00008.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow></mrow><mrow><mn>2</mn><mn>0</mn></mrow></msub></math></span><span></span> (Permalloy or Py) film. The growth of <span><math altimg=\"eq-00009.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><mi>α</mi><mo>+</mo><mi>β</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-<i>W</i> on the seed Py layer could be due to the strain that facilitates the mixed phase. <i>W</i> deposited on the Py layer is shown to be dependent on <span><math altimg=\"eq-00010.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>P</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">Ar</mtext></mstyle></mrow></msub></math></span><span></span>, in which the <span><math altimg=\"eq-00011.gif\" display=\"inline\" overflow=\"scroll\"><mi>β</mi></math></span><span></span>-<i>W</i> relative phase fraction is relative. A ferromagnetic resonance (FMR)-based spin pumping method was employed for spin current injection. The FMR linewidth (<span><math altimg=\"eq-00012.gif\" display=\"inline\" overflow=\"scroll\"><mi mathvariant=\"normal\">Δ</mi><mi>H</mi><mo stretchy=\"false\">)</mo></math></span><span></span> is enhanced for Py/<i>W</i> compared to the bare Py layer due to the spin current transport across the interface. The spin-mixing conductance (<span><math altimg=\"eq-00013.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>g</mi></mrow><mrow><mi>↑</mi><mi>↓</mi></mrow></msub><mo stretchy=\"false\">)</mo></math></span><span></span> is found to be a function of the relative phase fraction of <i>W</i>. The extracted <span><math altimg=\"eq-00014.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>g</mi></mrow><mrow><mi>↑</mi><mi>↓</mi></mrow></msub></math></span><span></span> is <span><math altimg=\"eq-00015.gif\" display=\"inline\" overflow=\"scroll\"><mn>4</mn><mo>.</mo><mn>9</mn><mn>0</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>1</mn><mn>8</mn></mrow></msup></math></span><span></span><span><math altimg=\"eq-00016.gif\" display=\"inline\" overflow=\"scroll\"><mspace width=\".17em\"></mspace></math></span><span></span>m<span><math altimg=\"eq-00017.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span><span></span> for <span><math altimg=\"eq-00018.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>P</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">Ar</mtext></mstyle></mrow></msub><mo>=</mo><mn>5</mn></math></span><span></span><span><math altimg=\"eq-00019.gif\" display=\"inline\" overflow=\"scroll\"><mspace width=\".17em\"></mspace></math></span><span></span>mTorr and <span><math altimg=\"eq-00020.gif\" display=\"inline\" overflow=\"scroll\"><mn>4</mn><mo>.</mo><mn>0</mn><mn>5</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>1</mn><mn>8</mn></mrow></msup></math></span><span></span><span><math altimg=\"eq-00021.gif\" display=\"inline\" overflow=\"scroll\"><mspace width=\".17em\"></mspace></math></span><span></span>m<span><math altimg=\"eq-00022.gif\" display=\"inline\" overflow=\"scroll\"><msup><mrow></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></math></span><span></span> for <span><math altimg=\"eq-00023.gif\" display=\"inline\" overflow=\"scroll\"><msub><mrow><mi>P</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">Ar</mtext></mstyle></mrow></msub><mo>=</mo><mn>1</mn><mn>0</mn></math></span><span></span><span><math altimg=\"eq-00024.gif\" display=\"inline\" overflow=\"scroll\"><mspace width=\".17em\"></mspace></math></span><span></span>mTorr. From the inverse spin Hall effect (ISHE) measurements, the effective spin Hall angle (<span><math altimg=\"eq-00025.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><msub><mrow><mi>θ</mi></mrow><mrow><mstyle><mtext mathvariant=\"normal\">SH</mtext></mstyle></mrow></msub><mo stretchy=\"false\">)</mo></math></span><span></span> is estimated to be <span><math altimg=\"eq-00026.gif\" display=\"inline\" overflow=\"scroll\"><mo>−</mo><mn>0</mn><mo>.</mo><mn>1</mn><mn>7</mn></math></span><span></span> for <span><math altimg=\"eq-00027.gif\" display=\"inline\" overflow=\"scroll\"><mi>α</mi></math></span><span></span>-<i>W</i> rich mixed phase of <span><math altimg=\"eq-00028.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><mi>α</mi><mo>+</mo><mi>β</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-<i>W</i>, whereas it is <span><math altimg=\"eq-00029.gif\" display=\"inline\" overflow=\"scroll\"><mo>−</mo><mn>0</mn><mo>.</mo><mn>1</mn><mn>0</mn></math></span><span></span> for <span><math altimg=\"eq-00030.gif\" display=\"inline\" overflow=\"scroll\"><mi>β</mi></math></span><span></span>-<i>W</i> rich <span><math altimg=\"eq-00031.gif\" display=\"inline\" overflow=\"scroll\"><mo stretchy=\"false\">(</mo><mi>α</mi><mo>+</mo><mi>β</mi><mo stretchy=\"false\">)</mo></math></span><span></span>-<i>W</i>. Our systematic study demonstrates the relatively large effective spin Hall angle via low-longitudinal resistivity by controlling the relative phase fraction of <i>W</i> and helps in developing energy-efficient spintronic devices.</p>","PeriodicalId":54319,"journal":{"name":"Spin","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Spin","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1142/s2010324723400271","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
Spin-to-charge conversion and vice versa due to spin-orbit coupling in ferromagnet-heavy metal heterostructure is of paramount interest for developing energy-efficient spintronic devices. Here, we have systematically investigated the effect of Ar deposition pressure ( on the tungsten (W) crystalline phase and extracted spin-dependent transport parameters. X-ray diffraction results show that 10nm-thick W films exhibit a structural phase transition from a mixed phase of -W to a single phase of -W as a function of . The observed phase transition is due to a decrease in adatom’s energy and surface mobility. Interestingly, only the -W phase is found to stabilize when W sputtered on a seed NiFe (Permalloy or Py) film. The growth of -W on the seed Py layer could be due to the strain that facilitates the mixed phase. W deposited on the Py layer is shown to be dependent on , in which the -W relative phase fraction is relative. A ferromagnetic resonance (FMR)-based spin pumping method was employed for spin current injection. The FMR linewidth ( is enhanced for Py/W compared to the bare Py layer due to the spin current transport across the interface. The spin-mixing conductance ( is found to be a function of the relative phase fraction of W. The extracted is m for mTorr and m for mTorr. From the inverse spin Hall effect (ISHE) measurements, the effective spin Hall angle ( is estimated to be for -W rich mixed phase of -W, whereas it is for -W rich -W. Our systematic study demonstrates the relatively large effective spin Hall angle via low-longitudinal resistivity by controlling the relative phase fraction of W and helps in developing energy-efficient spintronic devices.
SpinMaterials Science-Electronic, Optical and Magnetic Materials
CiteScore
2.10
自引率
11.10%
发文量
34
期刊介绍:
Spin electronics encompasses a multidisciplinary research effort involving magnetism, semiconductor electronics, materials science, chemistry and biology. SPIN aims to provide a forum for the presentation of research and review articles of interest to all researchers in the field.
The scope of the journal includes (but is not necessarily limited to) the following topics:
*Materials:
-Metals
-Heusler compounds
-Complex oxides: antiferromagnetic, ferromagnetic
-Dilute magnetic semiconductors
-Dilute magnetic oxides
-High performance and emerging magnetic materials
*Semiconductor electronics
*Nanodevices:
-Fabrication
-Characterization
*Spin injection
*Spin transport
*Spin transfer torque
*Spin torque oscillators
*Electrical control of magnetic properties
*Organic spintronics
*Optical phenomena and optoelectronic spin manipulation
*Applications and devices:
-Novel memories and logic devices
-Lab-on-a-chip
-Others
*Fundamental and interdisciplinary studies:
-Spin in low dimensional system
-Spin in medical sciences
-Spin in other fields
-Computational materials discovery