Rare-earth-free Mn-based binary alloy L1_(0)-MnAl with bulk perpendicular magnetic anisotropy(PMA) holds promise for high-performance magnetic random access memory(MRAM) devices driven by spin-orbit torque(SOT). Howev...Rare-earth-free Mn-based binary alloy L1_(0)-MnAl with bulk perpendicular magnetic anisotropy(PMA) holds promise for high-performance magnetic random access memory(MRAM) devices driven by spin-orbit torque(SOT). However, the lattice-mismatch issue makes it challenging to place conventional spin current sources, such as heavy metals, between L1_(0)-MnAl layers and substrates. In this work, we propose a solution by using the B2-CoGa alloy as the spin current source. The lattice-matching enables high-quality epitaxial growth of 2-nm-thick L1_(0)-MnAl on B2-CoGa, and the L1_(0)-MnAl exhibits a large PMA constant of 1.04 × 10^(6)J/m^(3). Subsequently, the considerable spin Hall effect in B2-CoGa enables the achievement of SOT-induced deterministic magnetization switching. Moreover, we quantitatively determine the SOT efficiency in the bilayer. Furthermore, we design an L1_(0)-MnAl/B2-CoGa/Co_(2)MnGa structure to achieve field-free magnetic switching. Our results provide valuable insights for achieving high-performance SOT-MRAM devices based on L1_(0)-MnAl alloy.展开更多
Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)A...Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)Al(CMA),is determined by x-ray photoelectron spectroscopy and energy dispersive spectroscopy. Tunable perpendicular magnetic anisotropy(PMA) from 3.41 Merg/cm^3 to 1.88 Merg/cm^3 with the thickness increasing from 10 nm to 30 nm is found,attributed to the relaxation of residual compressive strain. Moreover, comparing with the ultrathin CoFeB/MgO used in the conventional perpendicular magnetic tunnel junction, the CMA electrode has a higher magnetic thermal stability with more volume involved. The PMA in CMA films is sustainable up to 300℃,compatible with semiconductor techniques. This work provides a possibility for the development of perpendicular magnetized full-Heusler compounds with high thermal stability and spin polarization.展开更多
Perpendicularly magnetized L10-MnAl thin films with Co2 MnSi bufer layers were prepared on GaAs(001)substrates by molecular-beam epitaxy(MBE).The samples with high crystalline quality show a maximum uniaxial perpendic...Perpendicularly magnetized L10-MnAl thin films with Co2 MnSi bufer layers were prepared on GaAs(001)substrates by molecular-beam epitaxy(MBE).The samples with high crystalline quality show a maximum uniaxial perpendicular magnetic anisotropy constant of 1.4×10^7 erg/cm^3.Ultrafast spin dynamics with a magnetization precession frequency up to 200 GHz was investigated by using time-resolved magneto-optical Kerr effect(TRMOKE)measurements,from which the Gilbert damping constantαof epitaxial L10-MnAl thin films is evaluated to be less than 0.0175.This work provides an important reference for analyzing the current-induced magnetization switching process in MnAl-based spintronic devices.展开更多
We report on the tunneling anisotropic magnetoresistance in antiferromagnetic perpendicular tunnel junction consisting of L10-MnGa/FeMn/AlOx/Pt grown on GaAs（001） substrates by molecular-beam epitaxy. The temperatur...We report on the tunneling anisotropic magnetoresistance in antiferromagnetic perpendicular tunnel junction consisting of L10-MnGa/FeMn/AlOx/Pt grown on GaAs（001） substrates by molecular-beam epitaxy. The temperature-dependent perpendicular exchange bias effect reveals an exchange coupling between ferromagnetic L10-MnGa and antiferromagnetic FeMn. The rotation of antiferromagnetic spins in FeMn can be driven by perpendicularly magnetized L10-MnGa due to the exchange-spring effect at the interface and leads to roomtemperature tunneling anisotropic magnetoresistance ratio of 0.86%. We also find that the tunneling anisotropic magnetoresistance strongly depends on temperature and angle. These results have broadened the material selection range for high performance antiferromagnetic spintronic devices.展开更多
A synthetic antiferromagnet based on a thin antiferromagnetically coupled Co2MnSi/MnGa bilayer with Pt capping is proposed in this work. Square magnetic loops measured by anomalous Hall effect reveal that a well perpe...A synthetic antiferromagnet based on a thin antiferromagnetically coupled Co2MnSi/MnGa bilayer with Pt capping is proposed in this work. Square magnetic loops measured by anomalous Hall effect reveal that a well perpendicular magnetic anisotropy is obtained in this structure. A very large coercivity of 83 kOe (1 Oe = 79.5775 A⋅m^−1) is observed near the magnetic moment compensation point of 270 K, indicating an antiferromagnetic behavior. Moreover, the anomalous Hall signal does not go to zero even at the magnetic compensation point, for which the difficulty in detecting the conventional antiferromagnets can be overcome. By changing the temperature, the polarity of the spin–orbit torque induced switching is changed around the bilayer compensation point. This kind of thin bilayer has potential applications in spin–orbit-related effects, spintronic devices, and racetrack memories.展开更多
The performance of spin–orbit torque(SOT)in heavy metal/ferromagnetic metal periodic multilayers has attracted widespread attention.In this paper,we have successfully fabricated a series of perpendicular magnetized[P...The performance of spin–orbit torque(SOT)in heavy metal/ferromagnetic metal periodic multilayers has attracted widespread attention.In this paper,we have successfully fabricated a series of perpendicular magnetized[Pt(2-t)/Ni(t)]_4 multilayers,and studied the SOT in the multilayers by varying the thickness of Ni layer t.The current induced magnetization switching was achieved with a critical current density of 1×10^(7)A/cm^(2).The damping-like SOT efficiencyξ_(DL)was extracted from an extended harmonic Hall measurement.We demonstrated that theξ_(DL)can be effectively modulated by t_(Pt)/t_(Ni)ratio of Pt and Ni in the multilayers.The SOT investigation about the[Pt/Ni]N multilayers might provide new material candidates for practical perpendicular SOT-MRAM devices.展开更多
An ultra-thin Co2MnSi(0.5 nm)/Mn Ga(1.5 nm) bilayer capped with Pt(5 nm) has been successfully grown by molecular-beam epitaxy.It is a potential candidate of synthetic antiferromagnets due to antiferromagnetic couplin...An ultra-thin Co2MnSi(0.5 nm)/Mn Ga(1.5 nm) bilayer capped with Pt(5 nm) has been successfully grown by molecular-beam epitaxy.It is a potential candidate of synthetic antiferromagnets due to antiferromagnetic coupling between Co2MnSi and MnGa,which is a promising skyrmion-racetrack-memory medium without skyrmion Hall effect after capping with a Pt layer.Unusual humps in transverse Hall resistance loops are clearly observed in the temperature range from 260 to 400 K.This anomaly is generally attributed to topological Hall effect,but other than that,we prove that non-uniform rotation of magnetic moments in the bilayer with magnetic field sweeping is also a possible mechanism contributed to the unusual hump.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB44000000)。
文摘Rare-earth-free Mn-based binary alloy L1_(0)-MnAl with bulk perpendicular magnetic anisotropy(PMA) holds promise for high-performance magnetic random access memory(MRAM) devices driven by spin-orbit torque(SOT). However, the lattice-mismatch issue makes it challenging to place conventional spin current sources, such as heavy metals, between L1_(0)-MnAl layers and substrates. In this work, we propose a solution by using the B2-CoGa alloy as the spin current source. The lattice-matching enables high-quality epitaxial growth of 2-nm-thick L1_(0)-MnAl on B2-CoGa, and the L1_(0)-MnAl exhibits a large PMA constant of 1.04 × 10^(6)J/m^(3). Subsequently, the considerable spin Hall effect in B2-CoGa enables the achievement of SOT-induced deterministic magnetization switching. Moreover, we quantitatively determine the SOT efficiency in the bilayer. Furthermore, we design an L1_(0)-MnAl/B2-CoGa/Co_(2)MnGa structure to achieve field-free magnetic switching. Our results provide valuable insights for achieving high-performance SOT-MRAM devices based on L1_(0)-MnAl alloy.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2017YFB0405701 and2018YFB0407601the National Natural Science Foundation of China under Grant Nos U1632264 and 11874349the Key Research Project of Frontier Science of the Chinese Academy of Sciences under Grant Nos QYZDY-SSW-JSC015 and XDPB12
文摘Off-stoichiometric full-Heusler alloy Co_2 MnAl thin films with different thicknesses are epitaxially grown on GaAs(001) substrates by molecular-beam epitaxy. The composition of the films, close to Co_(1.65)Mn_(1.35)Al(CMA),is determined by x-ray photoelectron spectroscopy and energy dispersive spectroscopy. Tunable perpendicular magnetic anisotropy(PMA) from 3.41 Merg/cm^3 to 1.88 Merg/cm^3 with the thickness increasing from 10 nm to 30 nm is found,attributed to the relaxation of residual compressive strain. Moreover, comparing with the ultrathin CoFeB/MgO used in the conventional perpendicular magnetic tunnel junction, the CMA electrode has a higher magnetic thermal stability with more volume involved. The PMA in CMA films is sustainable up to 300℃,compatible with semiconductor techniques. This work provides a possibility for the development of perpendicular magnetized full-Heusler compounds with high thermal stability and spin polarization.
基金National Key R&D Program of China(Grant No.2018YFB0407601)Key Research Project of Frontier Science of Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-JSC015 and XDPB12)National Natural Science Foundation of China(Grant Nos.11834013,11874349,and 11774339)。
文摘Perpendicularly magnetized L10-MnAl thin films with Co2 MnSi bufer layers were prepared on GaAs(001)substrates by molecular-beam epitaxy(MBE).The samples with high crystalline quality show a maximum uniaxial perpendicular magnetic anisotropy constant of 1.4×10^7 erg/cm^3.Ultrafast spin dynamics with a magnetization precession frequency up to 200 GHz was investigated by using time-resolved magneto-optical Kerr effect(TRMOKE)measurements,from which the Gilbert damping constantαof epitaxial L10-MnAl thin films is evaluated to be less than 0.0175.This work provides an important reference for analyzing the current-induced magnetization switching process in MnAl-based spintronic devices.
基金Supported by the National Basic Research Program of China under Grant No 2015CB921500the National Natural Science Foundation of China under Grant Nos 61334006 and 11774339+1 种基金the Key Research Project of Frontier Science of the Chinese Academy of Sciences under Grant No QYZDY-SSW-JSC015the Key Research Program of the Chinese Academy of Sciences under Grant No XDPB08-2
文摘We report on the tunneling anisotropic magnetoresistance in antiferromagnetic perpendicular tunnel junction consisting of L10-MnGa/FeMn/AlOx/Pt grown on GaAs（001） substrates by molecular-beam epitaxy. The temperature-dependent perpendicular exchange bias effect reveals an exchange coupling between ferromagnetic L10-MnGa and antiferromagnetic FeMn. The rotation of antiferromagnetic spins in FeMn can be driven by perpendicularly magnetized L10-MnGa due to the exchange-spring effect at the interface and leads to roomtemperature tunneling anisotropic magnetoresistance ratio of 0.86%. We also find that the tunneling anisotropic magnetoresistance strongly depends on temperature and angle. These results have broadened the material selection range for high performance antiferromagnetic spintronic devices.
基金Project supported by the National Program on Key Basic Research Project,China(Grant No.2018YFB0407601)the Key Research Project of Frontier Science of the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-JSC015 and XDPB12)the National Natural Science Foundation of China(Grant Nos.11874349 and 11774339)。
文摘A synthetic antiferromagnet based on a thin antiferromagnetically coupled Co2MnSi/MnGa bilayer with Pt capping is proposed in this work. Square magnetic loops measured by anomalous Hall effect reveal that a well perpendicular magnetic anisotropy is obtained in this structure. A very large coercivity of 83 kOe (1 Oe = 79.5775 A⋅m^−1) is observed near the magnetic moment compensation point of 270 K, indicating an antiferromagnetic behavior. Moreover, the anomalous Hall signal does not go to zero even at the magnetic compensation point, for which the difficulty in detecting the conventional antiferromagnets can be overcome. By changing the temperature, the polarity of the spin–orbit torque induced switching is changed around the bilayer compensation point. This kind of thin bilayer has potential applications in spin–orbit-related effects, spintronic devices, and racetrack memories.
基金Project supported by the National Key R&D Program of China(Grant No.2021YFB3502400)the National Natural Science Foundation of China(Grant Nos.52061135105,12074025,11834013,and 12274203)+1 种基金the CAS Project for Yong Scientists in Basic Research(Grant No.YSBR-030)the Key Research Project of Frontier Science of Chinese Academy of Sciences(Grant Nos.XDB44000000 and XDB28000000)。
文摘The performance of spin–orbit torque(SOT)in heavy metal/ferromagnetic metal periodic multilayers has attracted widespread attention.In this paper,we have successfully fabricated a series of perpendicular magnetized[Pt(2-t)/Ni(t)]_4 multilayers,and studied the SOT in the multilayers by varying the thickness of Ni layer t.The current induced magnetization switching was achieved with a critical current density of 1×10^(7)A/cm^(2).The damping-like SOT efficiencyξ_(DL)was extracted from an extended harmonic Hall measurement.We demonstrated that theξ_(DL)can be effectively modulated by t_(Pt)/t_(Ni)ratio of Pt and Ni in the multilayers.The SOT investigation about the[Pt/Ni]N multilayers might provide new material candidates for practical perpendicular SOT-MRAM devices.
基金Supported by the National Program on Key Basic Research Project under Grant No.2018YFB0407601the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant Nos.XDB44000000 and QYZDY-SSW-JSC015the National Natural Science Foundation of China under Grant Nos.11874349 and 11774339。
文摘An ultra-thin Co2MnSi(0.5 nm)/Mn Ga(1.5 nm) bilayer capped with Pt(5 nm) has been successfully grown by molecular-beam epitaxy.It is a potential candidate of synthetic antiferromagnets due to antiferromagnetic coupling between Co2MnSi and MnGa,which is a promising skyrmion-racetrack-memory medium without skyrmion Hall effect after capping with a Pt layer.Unusual humps in transverse Hall resistance loops are clearly observed in the temperature range from 260 to 400 K.This anomaly is generally attributed to topological Hall effect,but other than that,we prove that non-uniform rotation of magnetic moments in the bilayer with magnetic field sweeping is also a possible mechanism contributed to the unusual hump.
