Spin injection, manipulation and detection are the integral parts of spintronics devices and have attracted tremendous attention in the last decade. It is necessary to judiciously choose the right combination of materials to have compatibility with the existing semiconductor technology. Conventional metallic magnets were the first choice for injecting spins into semiconductors in the past. So far there is no success in using a magnetic oxide material for spin injection, which is very important for the development of oxide based spintronics devices. Here we demonstrate the electrical spin injection from an oxide magnetic material Fe3O4, into GaAs with the help of tunnel barrier MgO at room temperature using 3-terminal Hanle measurement technique. A spin relaxation time τ ~ 0.9 ns for n-GaAs at 300 K is observed along with expected temperature dependence of τ. Spin injection using Fe3O4/MgO system is further established by injecting spins into p-GaAs and a τ of ~0.32 ns is obtained at 300 K. Enhancement of spin injection efficiency is seen with barrier thickness. In the field of spin injection and detection, our work using an oxide magnetic material establishes a good platform for the development of room temperature oxide based spintronics devices.

Interface effect in complex oxide thin film heterostructures lies at the vanguard of current research to design technologically relevant functionality and explore emergent physical phenomena. While most of the previous works focus on the perovskite/perovskite heterostructures, the study on perovskite/brownmillerite interfaces remain at its infancy. Here, we investigate spontaneously stabilized perovskite-ferromagnet (SrCoO 3-δ )/brownmillertiteantiferromagnet (SrCoO 2.5 ) bi-layer with T N > T C and discover an unconventional interfacial magnetic exchange bias effect. From magnetometry investigations, it is rationalized that the observed effect stems from the interfacial ferromagnet/antiferromagnet coupling. The possibility for coupled ferromagnet/spinglass interface engendering such effect is ruled out.Strikingly, a finite coercive field persists in the paramagnetic state of SrCoO 3-δ whereas the exchange bias field vanishes at T C . We conjecture the observed effect to be due to the effective external quenched staggered field provided by the antiferromagtic layer for the ferromagnetic spins at the interface. Our results not only unveil a new paradigm to tailor the interfacial magnetic properties in oxide heterostructures without altering the cations at the interface, but also provide a purview to delve into the fundamental aspects of exchange bias in such unusual systems paving a big step forward in thin film magnetism.1 The investigation on interfacial magnetic effects in transition metal oxide based thin film heterostructures has sparked unprecedented scientific developments and is pursued intensively because of its technological promise for the next-generation nano-scaled magnetic devices [1]. A precise control and tuning of interfacial magnetic properties in thin film heterostructures is crucial for engendering exotic functionalities which are highly relevant for technological applications such as magnetic field sensors, memories or magnetic recording read heads [2][3][4]. A great deal of attention in this regard is focused on the effect called "exchange bias" that occurs due to interfacial magnetic exchange coupling in a coupled ferromagnetic/antiferromagnetic system [5,6]. This effect is widely maneuvered for the design and operation of spin valve based magnetic read heads and sensors. The macroscopic hallmark of magnetic exchange bias effect (MEBE) is the unidirectional shift of the M(H) loop along the field-axis (Figure1(c)), and enhancement of coercivity. Typically, a bi-layer consisting of a FM and an AF (with the Curie temperature (T C ) of FM greater than the Néel temperature (T N ) of AF) when cooled in a static magnetic field across the T N , an unidirectional exchange anisotropy-fieldgets locked in and give rise to exchange bias effectthat stabilizes the orientation of the ferromagnetic layer [2,7,8]. Such systems exhibit magnetic properties that markedly differ from their constituents. Though exchange bias related phenomena in FM/AFM coupled system is studied extensively, its inherent mechanism ...

2H-NbSe 2 is known to be an archetype layered transitional metal dichalcogenide superconductor with a superconducting transition temperature of 7.3 K.In this article, we investigate the influence of Sn intercalation on superconducting properties of 2H-NbSe 2 . Sn being nonmagnetic and having no outer shell d-electronsunlike transition metals, one naively would presume that its effect on superconducting properties will be very marginal. However, our magnetic and transport studies reveal a significant reduction of both superconducting transition temperature and upper critical field [T c and B C2 (0)] upon Sn intercalation. With a mere 4 mole% Sn intercalation, it is observed that T c and B C2 (0) get suppressed by ~3.5K and 3T, respectively. Werthamer-Helfand-Hohenberg (WHH) analysis of magneto-transport data is performed to estimateB C2 (0). From the low temperature Raman scattering data in the normal phase of intercalated NbSe 2 , it is inferred that the suppression of superconductivity cannot be ascribed to strengthening of charge density wave (CDW)ordering. The effects such as electron-doping induced Fermi surface change and/or disorder scattering upon intercalation are speculated to be at play for the observed phenomena.

Metastable orthorhombic SrIrO3 (SIO) is an arch-type spin-orbit coupled material. We demonstrate here a controlled growth of relatively thick (200 nm) SIO films that transform from bulk “6H-type” structure with monoclinic distortion to an orthorhombic lattice by controlling growth temperature. Extensive studies based on high-resolution X-ray diffraction and transmission electron microscopy infer a two distinct structural phases of SIO. Electrical transport reveals a weak temperature-dependent semi-metallic character for both phases. However, the temperature-dependent Hall-coefficient for the orthorhombic SIO exhibits a prominent sign change, suggesting a multiband character in the vicinity of EF. Our findings thus unravel the subtle structure-property relation in SIO epitaxial thin films.

Half-metal based spin injector devices for spin injection and detection application have proven to be efficient owing to their enhanced injection and detection efficiency. In this study, we extend the all-electrical spin injection and detection studies into different systems like Si and GaAs using half-metal Fe3O4 as a spin injector in the presence and absence of tunnel barrier MgO. Injection into GaAs is verified using conventional Fe/MgO/GaAs devices. Room temperature spin injection into both p-type and n-type Si is achieved and the spin injection could be observed down to 100K. Obtained spin relaxation time for these n-type and p-type Si at different temperatures agree well with the existing reports. Further, the temperature dependent spin injection and detection is also successfully achieved in Fe3O4/GaAs (n-type) Schottky devices, and a comparison study of the results with control experiment using Fe/MgO/GaAs (n-type) devices confirm the relaxation to be similar in the GaAs substrate, as expected. Hence, even Fe3O4 material can be effectively used as an efficient spin injector as well as detector, making it an attractive candidate for the room temperature spintronics device applications.