Abstract
Perpendicular magnetic anisotropy and perpendicular exchange bias of CoPt/FeMn bilayers fabricated by dc magnetron sputtering were investigated in this work. Magnetic anisotropy, showing strong dependence on thickness of CoPt layer, changes from perpendicular magnetic anisotropy (PMA) into in-plane magnetic anisotropy when CoPt layer is thicker than 4.5 nm. The evolution of internal stress with thickness, from tensile to compressive, has been analyzed by sin2ψ method using an equal biaxial stress model. Distinctive perpendicular exchange bias (PEB) has been successfully established due to PMA of CoPt and out-of-plane spin component of 3Q-spin-structured FeMn. FeMn thickness dependence of exchange bias field has been systematically investigated.
Similar content being viewed by others
References
Phuoc N N, Suzuki T. Perpendicular exchange bias mechanism in FePt/FeMn multilayers. J Appl Phys, 2007, 101: 09E501
van den Brink A, Vermijs G, Solignac A, et al. Field-free magnetization reversal by spin-Hall effect and exchange bias. Nat Commun, 2016, 7: 10854
Zhang W, Han W, Yang S H, et al. Giant facet-dependent spin-orbit torque and spin Hall conductivity in the triangular antiferromagnet IrMn3. Sci Adv, 2016, 2: e1600759
Ma X, Yu G, Razavi S A, et al. Dzyaloshinskii-Moriya interaction across an antiferromagnet-ferromagnet interface. Phys Rev Lett, 2017, 119: 027202
An H, Ando K, Nakamura Y, et al. Formation and perpendicular magnetic coupling of A1 and L10 CoPt in CoPt/TiN films on glass substrate. IEEE Trans Magn, 2018, 55: 1–4
Liu D, Liu X M, Liu G Q, et al. Phase stability and magnetic performance of nanocrystalline Sm-Co supersaturated solid solution. Sci China Tech Sci, 2018, 61: 129–134
Ahn S M, Beach G S D. Crossover between in-plane and perpendicular anisotropy in Ta/CoxFe100-x/MgO films as a function of Co composition. J Appl Phys, 2013, 113: 17C112
Basile F, Poix P. Etude par effect Mössbauer et mesures magnétiques de la solution solide Fe2−2xMg1+xSnxO4. Phys Stat Sol (a), 1976, 35: 153–164
Lisfi A, Williams C M, Nguyen L T, et al. Reorientation of magnetic anisotropy in epitaxial cobalt ferrite thin films. Phys Rev B, 2007, 76: 054405
Niizeki T, Utsumi Y, Aoyama R, et al. Extraordinarily large perpendicular magnetic anisotropy in epitaxially strained cobalt-ferrite CoxFe3−2xO4 (001) (x = 0.75, 1.0) thin films. Appl Phys Lett, 2013, 103: 162407
Numata Y, Itabashi A, Ohtake M, et al. Structural characterization of FePd, FePt, and CoPt alloy thin filmsepitaxially groown on (001) surface of different single-crystal materials. IEEE Trans Magn, 2013, 50: 1–4
Phuoc N N, Chen H Y, Ong C K. Effect of antiferromagnetic thickness on thermal stability of static and dynamic magnetization of NiFe/FeMn multilayers. J Appl Phys, 2013, 113: 063913
Martínez-Boubeta C, Botana A S, Pardo V, et al. Heteroepitaxial growth of MgO(111) thin films on Al2O3 (0001): Evidence of a wurtzite to rocksalt transformation. Phys Rev B, 2012, 86: 041407
Yu Y, Shi J, Nakamura Y. Thickness-dependent perpendicular magnetic anisotropy of CoPt top layer on CoPt/AlN multilayer. IEEE Trans Magn, 2010, 46: 1663–1666
Pan C, Gao T, Harumoto T, et al. Asymmetry in magnetic behavior caused by superposition of unidirectional and four-fold magnetic anisotropies in CoPt/FeMn bilayers. Appl Surf Sci, 2019, 480: 148–153
Guo L, Wang Y, Wang J, et al. Magnetoelastically induced perpendicular magnetic anisotropy and perpendicular exchange bias of CoO/CoPt multilayer films. J Magn Magn Mater, 2015, 394: 349–353
Nogués J, Schuller I K. Exchange bias. J Magn Magn Mater, 1999, 192: 203–232
Zhao X P, Lu J, Mao S W, et al. Spontaneous perpendicular exchange bias effect in L 10-MnGa/FeMn bilayers grown by molecular-beam epitaxy. Appl Phys Lett, 2018, 112: 042403
Lenz K, Zander S, Kuch W. Magnetic proximity effects in antiferromagnet/ferromagnet bilayers: The impact on the Néel temperature. Phys Rev Lett, 2007, 98: 237201
** H, White R M, Mao S, et al. Low-frequency dynamic hysteresis in exchange-coupled Ni81Fe19/Ir22Mn78 bilayers. Phys Rev B, 2001, 64: 184416
Bolon B T, Haugen M A, Abin-Fuentes A, et al. Multiple antiferromagnet/ferromagnet interfaces as a probe of grain-size-dependent exchange bias in polycrystalline Co/Fe50Mn50. J Magn Magn Mater, 2007, 309: 54–63
Chang H W, Yuan F T, Chiang M T, et al. Effect of Ta underlayer on magnetic properties of FeMn/NiFe films. Surf Coatings Tech, 2016, 303: 148–153
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Pan, C., Gao, T., Itogawa, N. et al. Large lattice mismatch induced perpendicular magnetic anisotropy and perpendicular exchange bias in CoPt/FeMn bilayer films. Sci. China Technol. Sci. 62, 2009–2013 (2019). https://doi.org/10.1007/s11431-019-1433-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11431-019-1433-0