logo

SCIENCE CHINA Materials, Volume 64 , Issue 8 : 2029-2036(2021) https://doi.org/10.1007/s40843-020-1574-5

Giant spin torque efficiency in single-crystalline antiferromagnet Mn2Au films

More info
  • ReceivedOct 22, 2020
  • AcceptedNov 24, 2020
  • PublishedFeb 4, 2021

Abstract


Funding

the Agency for Science

Technology and Research(A*STAR)

the Singapore Ministry of Education(MOE2018-T2-2-043)

and A*STAR IAF-ICP 11801E0036.


Acknowledgment

This work was supported by the Agency for Science, Technology and Research (A*STAR) of Singapore (A1983c0036), the Singapore Ministry of Education (MOE2018-T2-2-043), and A*STAR IAF-ICP 11801E0036.


Interest statement

The authors declare that they have no conflict of interest.


Contributions statement

Chen S prepared the samples. Chen S and Shu X designed and performed the measurements; Chen S, Shu X and Zhou J performed the data analysis; Chen S, Shu X and Chen J wrote and revised the paper. All authors contributed to the general discussion.


Author information

Shaohai Chen is a research fellow of the National University of Singapore. He received a PhD degree in 2016 from Fudan University. During 2014–2015, he was a joint-training PhD student at the National University of Singapore. His research interest focuses on high-anisotropy magnetic materials, 2D materials and spintronics.


Xinyu Shu received his Bachelor degree from Harbin Institute of Technology and Master degree from Beijing University of Technology. He is now a PhD candidate at the Department of Material Science and Engineering, National University of Singapore. His current research interest is spintronics in metallic, oxide and low dimension heterostructures.


Jingsheng Chen received his PhD degree from Lanzhou University, China, in 1999. He joined Nanyang Technological University as a post-doctor in 1999–2001 and the Data Storage Institute, A*STAR as research scientist in 2001–2007. In the year of 2007, he joined the National University of Singapore as an assistant professor and was promoted to associate professor in 2013. His research interest includes high-anisotropy magnetic materials, spintronics, multiferroic materials, and nanostructure magnetic materials.


Supplementary data

Supplementary information

Experimental details and supporting data are available in the online version of the paper.


References

[1] Olejník K, Schuler V, Marti X, et al. Antiferromagnetic CuMnAs multi-level memory cell with microelectronic compatibility. Nat Commun, 2017, 815434 CrossRef PubMed ADS Google Scholar

[2] Železný J, Wadley P, Olejník K, et al. Spin transport and spin torque in antiferromagnetic devices. Nat Phys, 2018, 14220-228 CrossRef ADS Google Scholar

[3] Němec P, Fiebig M, Kampfrath T, et al. Antiferromagnetic opto-spintronics. Nat Phys, 2018, 14229-241 CrossRef Google Scholar

[4] Šmejkal L, Mokrousov Y, Yan B, et al. Topological antiferromagnetic spintronics. Nat Phys, 2018, 14242-251 CrossRef Google Scholar

[5] Tokura Y, Yasuda K, Tsukazaki A. Magnetic topological insulators. Nat Rev Phys, 2019, 1126-143 CrossRef ADS Google Scholar

[6] Manchon A, Železný J, Miron I , et al. Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems. Rev Mod Phys, 2019, 91035004 CrossRef ADS arXiv Google Scholar

[7] Zhu L, Buhrman RA. Maximizing spin-orbit-torque efficiency of Pt/Ti multilayers: Trade-off between intrinsic spin hall conductivity and carrier lifetime. Phys Rev Appl, 2019, 12051002 CrossRef ADS arXiv Google Scholar

[8] Liu L, Pai CF, Li Y, et al. Spin-torque switching with the giant spin hall effect of tantalum. Science, 2012, 336555-558 CrossRef PubMed ADS arXiv Google Scholar

[9] Chen S, Yu J, Xie Q, et al. Free field electric switching of perpendicularly magnetized thin film by spin current gradient. ACS Appl Mater Interfaces, 2019, 1130446-30452 CrossRef PubMed Google Scholar

[10] Shu X, Zhou J, Deng J, et al. Spin-orbit torque in chemically disordered and L11-ordered Cu100−xPtx. Phys Rev Mater, 2019, 3114410 CrossRef ADS Google Scholar

[11] Xie Q, Lin W, Yang B, et al. Giant enhancements of perpendicular magnetic anisotropy and spin-orbit torque by a MoS2 layer. Adv Mater, 2019, 311900776 CrossRef PubMed Google Scholar

[12] Zhu L, Sobotkiewich K, Ma X, et al. Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd1−xPtx alloys. Adv Funct Mater, 2019, 291805822 CrossRef Google Scholar

[13] Ou Y, Shi S, Ralph DC, et al. Strong spin hall effect in the antiferromagnet PtMn. Phys Rev B, 2016, 93220405 CrossRef ADS arXiv Google Scholar

[14] Zhou J, Wang X, Liu Y, et al. Large spin-orbit torque efficiency enhanced by magnetic structure of collinear antiferromagnet IrMn. Sci Adv, 2019, 5eaau6696 CrossRef PubMed ADS Google Scholar

[15] Zhou J, Shu X, Liu Y, et al. Magnetic asymmetry induced anomalous spin-orbit torque in IrMn. Phys Rev B, 2020, 101184403 CrossRef ADS arXiv Google Scholar

[16] Zhang W, Han W, Yang SH, et al. Giant facet-dependent spin-orbit torque and spin Hall conductivity in the triangular antiferromagnet IrMn3. Sci Adv, 2016, 2e1600759 CrossRef PubMed ADS Google Scholar

[17] DuttaGupta S, Kanemura T, Zhang C, et al. Spin-orbit torques and Dzyaloshinskii-Moriya interaction in PtMn/[Co/Ni] heterostructures. Appl Phys Lett, 2017, 111182412 CrossRef ADS Google Scholar

[18] Lin PH, Yang BY, Tsai MH, et al. Manipulating exchange bias by spin-orbit torque. Nat Mater, 2019, 18335-341 CrossRef PubMed ADS Google Scholar

[19] Shick AB, Khmelevskyi S, Mryasov ON, et al. Spin-orbit coupling induced anisotropy effects in bimetallic antiferromagnets: A route towards antiferromagnetic spintronics. Phys Rev B, 2010, 81212409 CrossRef ADS arXiv Google Scholar

[20] Wu HC, Abid M, Kalitsov A, et al. Anomalous anisotropic magnetoresistance of antiferromagnetic epitaxial bimetallic films: Mn2Au and Mn2Au/Fe bilayers. Adv Funct Mater, 2016, 265884-5892 CrossRef Google Scholar

[21] Singh BB, Bedanta S. Large spin Hall angle and spin-mixing conductance in the highly resistive antiferromagnet Mn2Au. Phys Rev Appl, 2020, 13044020 CrossRef ADS Google Scholar

[22] Bodnar SY, Šmejkal L, Turek I, et al. Writing and reading antiferromagnetic Mn2Au by Néel spin-orbit torques and large anisotropic magnetoresistance. Nat Commun, 2018, 9348 CrossRef PubMed ADS arXiv Google Scholar

[23] Chen XZ, Zarzuela R, Zhang J, et al. Antidamping-torque-induced switching in biaxial antiferromagnetic insulators. Phys Rev Lett, 2018, 120207204 CrossRef PubMed ADS arXiv Google Scholar

[24] Meinert M, Graulich D, Matalla-Wagner T. Electrical switching of antiferromagnetic Mn2Au and the role of thermal activation. Phys Rev Appl, 2018, 9064040 CrossRef ADS arXiv Google Scholar

[25] Zhou XF, Zhang J, Li F, et al. Strong orientation-dependent spin-orbit torque in thin films of the antiferromagnet Mn2Au. Phys Rev Appl, 2018, 9054028 CrossRef ADS arXiv Google Scholar

[26] Chen X, Zhou X, Cheng R, et al. Electric field control of Néel spin-orbit torque in an antiferromagnet. Nat Mater, 2019, 18931-935 CrossRef PubMed ADS Google Scholar

[27] Barthem VMTS, Colin CV, Mayaffre H, et al. Revealing the properties of Mn2Au for antiferromagnetic spintronics. Nat Commun, 2013, 42892 CrossRef PubMed ADS Google Scholar

[28] Wu HC, Liao ZM, Sofin RGS, et al. Mn2Au: Body-centered-tetragonal bimetallic antiferromagnets grown by molecular beam epitaxy. Adv Mater, 2012, 246374-6379 CrossRef PubMed Google Scholar

[29] Wu F, Sajitha EP, Mizukami S, et al. Electrical transport properties of perpendicular magnetized Mn-Ga epitaxial films. Appl Phys Lett, 2010, 96042505 CrossRef ADS Google Scholar

[30] Zhu L, Nie S, Meng K, et al. Multifunctional L10-Mn1.5Ga films with ultrahigh coercivity, giant perpendicular magnetocrystalline anisotropy and large magnetic energy product. Adv Mater, 2012, 244547-4551 CrossRef PubMed Google Scholar

[31] Meng K, Miao J, Xu X, et al. Modulated switching current density and spin-orbit torques in MnGa/Ta films with inserting ferromagnetic layers. Sci Rep, 2016, 638375 CrossRef PubMed ADS Google Scholar

[32] Ranjbar R, Suzuki KZ, Sasaki Y, et al. Current-induced spin-orbit torque magnetization switching in a MnGa/Pt film with a perpendicular magnetic anisotropy. Jpn J Appl Phys, 2016, 55120302 CrossRef ADS Google Scholar

[33] Pai CF, Ou Y, Vilela-Leão LH, et al. Dependence of the efficiency of spin Hall torque on the transparency of Pt/ferromagnetic layer interfaces. Phys Rev B, 2015, 92064426 CrossRef ADS arXiv Google Scholar

[34] Pechan MJ, Bennett D, Teng N, et al. Induced anisotropy and positive exchange bias: A temperature, angular, and cooling field study by ferromagnetic resonance. Phys Rev B, 2002, 65064410 CrossRef ADS Google Scholar

[35] Sapozhnik AA, Filianina M, Bodnar SY, et al. Direct imaging of antiferromagnetic domains in Mn2Au manipulated by high magnetic fields. Phys Rev B, 2018, 97134429 CrossRef ADS arXiv Google Scholar

[36] Zhang W, Jungfleisch MB, Freimuth F, et al. All-electrical manipulation of magnetization dynamics in a ferromagnet by antiferromagnets with anisotropic spin Hall effects. Phys Rev B, 2015, 92144405 CrossRef ADS arXiv Google Scholar

[37] Liu L, Yu J, González-Hernández R, et al. Electrical switching of perpendicular magnetization in a single ferromagnetic layer. Phys Rev B, 2020, 101220402 CrossRef ADS arXiv Google Scholar

[38] Zhang PX, Liao LY, Shi GY, et al. Spin-orbit torque in a completely compensated synthetic antiferromagnet. Phys Rev B, 2018, 97214403 CrossRef ADS arXiv Google Scholar

[39] Ishikuro Y, Kawaguchi M, Taniguchi T, et al. Highly efficient spin-orbit torque in Pt/Co/Ir multilayers with antiferromagnetic interlayer exchange coupling. Phys Rev B, 2020, 101014404 CrossRef ADS arXiv Google Scholar

[40] Sato T, Seki T, Kohda M, et al. Evaluation of spin-orbit torque in a L10-FePt single layer and a L10-FePt/Pt bilayer. Jpn J Appl Phys, 2019, 58060915 CrossRef ADS Google Scholar

  • Figure 1

    (a, b) XRD spectra of the STO-sub and Si-sub samples, respectively. The schematic in (b) shows the sample structure.

  • Figure 2

    (a, b) ST-FMR spectra of the STO-sub and Si-sub samples with f ranging from 4 to 12 GHz, respectively. (c) Schematic and image of the device for the ST-FMR measurements. (d, e) The Vmix (circles) versus the Hex curves with f = 9 GHz and corresponding fitting results for the Si-sub and STO-sub samples, respectively. The dotted and dashed lines correspond to the contributions of VA and Vs, respectively. (f) The f versus Hres curves and corresponding fitting lines of the two samples with different substrates.

  • Figure 3

    (a) The dependence of ξDL on the in-plane angle φm of the STO-sub and MgO-sub samples. The insert schematic shows the relation between the φm and the [100] orientation of the substrate. The x-axis is parallel to the long side of the device strip. (b) The resistivities of the Mn2Au films deposited on different substrates. The insert schematic shows the dual magnetic easy axes directions of the (002)-oriented single-crystal Mn2Au film.

  • Figure 4

    (a) Schematic showing how the Mn2Au layer induces a spin current and forms torques on the MnGa layer. (b) The AHE measurement result of the sample. (c) The current induced magnetization switching results of the sample with different external magnetic fields Hx along the current direction. (d) The extracted critical switching current density Jc versus Hx curve from (c).

  • Table 1   Summary of the resistivity (ρxx), spin Hall conductivity (σSH) and effective SOT efficiency (ξDL) of the AFM materials with single-crystalline and polycrystalline structures of our work and recently reported results

    Material

    ρxx

    (µΩ cm)

    σSH

    (103(ħ/2e) Ω−1 cm−1)

    ξDL

    Refs

    Mn2Au (single-crystalline)

    176

    >3.10

    0.731

    This work

    Mn2Au (polycrystalline)

    370

    <0.23

    0.051

    This work

    Mn2Au (single-crystalline)

    150

    1.46

    0.22

    [22]

    IrMn (single-crystalline)

    ~85

    ~7

    0.6

    [14,15]

    IrMn (polycrystalline)

    173

    0.58

    0.09

    [14,16]

    IrMn3 (single-crystalline)

    160

    2.19

    0.3

    [16]

    IrMn3 (polycrystalline)

    183

    0.55

    0.10

    [16]

    PtMn (single-crystalline)

    180

    0.29

    0.052

    [36]

    PtMn (polycrystalline)

    ~140

    ~1.5

    0.24

    [13]

    PdMn (single-crystalline)

    270

    0.12

    0.032

    [36]

qqqq

Contact and support