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In superconducting/ferromagnet heterostructures, spin-triplet Cooper pairs that carry spin information are crucial for the realization of superconducting spintronics. It has been theoretically proposed that they can be generated and controlled by the magnetic proximity effect and spin–orbit coupling (SOC), resulting in a change in the critical temperature (T C). However, experiments are still lacking, which limits the development of device applications. Here, we fabricate a series of Co/Nb/Pt heterostructures and reference samples, where the SOC and magnetic proximity can be independently controlled. We found the suppression of T C up to 11% by the different Rashba-SOC at the Nb/Pt and Nb/Cu interfaces, and the normalized T C/T C 0 was successfully tuned by 24% with the coeffect of SOC and magnetic proximity. Through rigorous comparison, we attribute the tuning of superconductivity to the spin-triplet Cooper pairs, which is controlled by both the SOC strength and magnetic proximity. Our results offer a new pathway to control superconductivity with SOC and pave a new direction for the design of superconducting spintronics devices.

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.

An ultra-thin Co2MnSi(0.5 nm)/MnGa(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.

Perpendicularly magnetized L10 -MnAl thin films with Co 2 MnSi buffer 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 × 107 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 constant α of 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.

We report on the tunneling magnetoresistance (TMR) effect in fully perpendicular magnetic tunnel junctions (p-MTJs) with the core structure of L10-MnAl/MgO/Co2MnSi/MnAl. The multilayer is epitaxially grown on GaAs (0 0 1) substrate by molecular-beam epitaxy (MBE), and both the top and bottom MnAl layers show well perpendicular magnetic anisotropy (PMA). Meanwhile, an inverse TMR effect with the MR ratio of 10% is observed at 5 K, which is attributed to the intrinsic negative spin polarization of MnAl in contrast to the positive one in Co2MnSi. This work proposes a MnAl-based fully p-MTJ for future STT-MRAM applications.

Off-stoichiometric full-Heusler alloy Co2MnAl thin films with different thicknesses are epitaxially grown on GaAs (001) substrates by molecular-beam epitaxy. The composition of the films, close to Co1.65Mn1.35Al (CMA), is determined by x-ray photoelectron spectroscopy and energy dispersive spectroscopy. Tunable perpendicular magnetic anisotropy (PMA) from 3.41 Merg/cm3 to 1.88 Merg/cm3 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°C, 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.

We report on the investigation of the magnetic tunnel junction structure designed for high magnetic field sensors with a perpendicularly magnetized L10-MnGa reference layer and an in-plane magnetized Fe sensing layer. A large linear tunneling magnetoresistance ratio up to 27.4% and huge dynamic range up to 5600 Oe have been observed at 300 K, with a low nonlinearity of 0.23% in the optimized magnetic tunnel junction (MTJ). The field response of tunneling magnetoresistance is discussed to explain the field sensing properties in the dynamic range. These results indicate that L10-MnGa based orthogonal MTJ is a promising candidate for a high performance magnetic field sensor with a large dynamic range, high endurance and low power consumption.

We have studied the magnetic properties of Co (2–12 MLs)/L10-Mn1.5Ga (15 nm) bilayers without and with annealing at 300 °C by a combination of superconducting quantum interference device (SQUID) magnetometry and x-ray magnetic circular dichroism (XMCD). We find that the Co layer can remain perpendicularly magnetized when its thickness is less than six monolayers due to the coupling between Co and L10-Mn1.5Ga layers, which is doubly confirmed by both SQUID and XMCD measurements. Such an exchange coupling between L10-Mn1.5Ga and Co layers changes from ferromagnetic coupling to antiferromagnetic coupling after the annealing process. Furthermore, the magnetic coupling can also be tailored from ferromagnetic to antiferromagnetic by changing the L10-Mn1.5Ga surface from Mn-rich to Ga-rich. The first-principles calculations show that the interfacial coupling type is ferromagnetic for a Mn-terminated L10-Mn1.5Ga bilayer, while antiferromagnetic for a Ga-terminated bilayer. The spin and orbital moments of Co in the Co/L10-Mn1.5Ga bilayers are calculated according to the sum rules and the ratio of the orbital to spin magnetic moments for Co is not enhanced like other perpendicularly magnetized Co-based multilayers such as Co/Pd and Co/Pt.

The anomalous Hall effect in epitaxial face-centered-cubic Co film grown by molecular beam epitaxy on MgO(001) is investigated. The intrinsic anomalous Hall conductivity is separated from the scattering-related extrinsic contributions and determined to be 727 Ω(-1) cm(-1) and temperature independent. This result provides well defined experimental data for further theoretical justification.