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Asymmetric heterointerfaces that bridge two nonisostructural oxides provide valuable opportunities for novel emergent phenomena that may be unavailable for symmetric interfaces. Here we present a theoretical investigation on three different asymmetric interfaces consisting of the infinite-layer nickelate $\mathrm{LaNi}{\mathrm{O}}_{2}$ and the perovskite manganite $\mathrm{LaMn}{\mathrm{O}}_{3}$ (type A, B and C). An alternative crystal geometry, pyramid, is introduced when the planar-type $\mathrm{LaNi}{\mathrm{O}}_{2}$ and the $\mathrm{LaMn}{\mathrm{O}}_{3}$ are jointed at the interface, resulting in strong charge and orbital reconstruction. For type A interface, the magnetic moment per Mn ion has increased by 10% due to the replacement of $\mathrm{Mn}{\mathrm{O}}_{6}$ by $\mathrm{Mn}{\mathrm{O}}_{5}$. For type B interface, in contrast, the magnetic moment grew by 26% for the interfacial Ni ions due to the strong charge transfer between center nickel and apical oxygen. For type C interface, only slightly enhanced $\mathrm{Mn}{\mathrm{O}}_{6}$ distortions are observed and thus the change of charge and orbital occupancy are negligible. Our results demonstrated that an interface-selective orbital occupancy, where the Mn ${e}_{\mathrm{g}}$ orbital preferential occupation alternated from the out-of-plane ${\mathrm{d}}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ state at type A interface to nearly degenerate at type C interface and then to in-plane ${\mathrm{d}}_{{x}^{2}\ensuremath{-}{y}^{2}}$ state at type B interface. The values of relative change of Mn ${e}_{\mathrm{g}}$ orbital occupancy are 15%, 2%, and \ensuremath{-}21%, respectively. The values of relative change at type A and B interface are larger than that achieved by strain $(\ensuremath{\sim}5%)$ or symmetric interface design (10%). Therefore, interface reconstructions lead to unusual electronic properties, opening space for the advancement of oxide electronics.

Bilinear magnetoresistance (BMR), the magnetoresistance that is linear against either magnetic field or applied current, is a hot topic of recent investigations. While most of the previous works focused on isotropic BMR, here we report on a strongly anisotropic BMR for (110) $\mathrm{SrTi}{\mathrm{O}}_{3}$-based two-dimensional electron gas (2DEG). Remarkably, the BMR measured along the [001] axis can be fivefold as large as that obtained along the $[1\overline{1}0]$ axis. A close relation is found between BMR and current-induced effective Rashba field, and it is the anisotropy of the Rashba field that causes the anisotropic BMR. Based on the analysis of anisotropic magnetoresistance, effective Rashba fields up to 4.5 T are determined. The band structure of the 2DEG is further calculated, ellipse-shaped Fermi rings are obtained, and the respective effects of different Fermi rings on BMR are distinguished. This work demonstrates the great potential of anisotropic 2DEG for the exploration of unusual effects.

Investigation on terahertz (THz) emission is important not only for fundamental research but also for practical application. A rapidly developing approach to generate THz emission is using a heterostructure composed of ferromagnetic metal (FM) and nonmagnetic metal (NM) which is pumped by femtosecond laser pulse. Previous works in this regard mainly focused on bilayer with heavy NM (such as Pt) with a large spin Hall angle. Here we present a comprehensive investigation on THz emission from Co/Al heterostructures stemming from the inverse spin Hall effect. It is surprising to find that although the spin Hall angle of Al is two orders of magnitude smaller than that of Pt, the measured THz signals are close to one-third of that of the typical Co/Pt heterostructures. To explore the underlying physics, theoretical models are employed to investigate the spin-related properties of Al. We obtain that the upper limit of the spin Hall angle of Al is 0.55% and the spin-diffusion length is 2.2 \ifmmode\pm\else\textpm\fi{} 0.2 nm; the diffusion length is comparable to that of Pt (2.3 \ifmmode\pm\else\textpm\fi{} 0.1 nm). This work shows that it is worth revisiting light metals for the spintronic THz emitter.

Based on density functional theory calculations, we show how symmetry mismatch at interface induces perpendicular magnetic anisotropy (PMA) for the perovskite/brownmillerite-typed $\mathrm{L}{\mathrm{a}}_{1/2}\mathrm{S}{\mathrm{r}}_{1/2}\mathrm{Mn}{\mathrm{O}}_{3}/\mathrm{LaCo}{\mathrm{O}}_{2.5}$ superlattices in different strain states. We found strong interfacial reconstructions, which result in considerable orbital hybridization due to distortion/tilting of the $\mathrm{Mn}{\mathrm{O}}_{6}$ octahedron and $\mathrm{Co}{\mathrm{O}}_{4}$ tetrahedron. We identified the orbital pairs that strongly affect magnetic anisotropy, showing that tuning the degree of orbital hybridization by lattice strain is an effective approach to tune magnetic anisotropy. Remarkably, not only octahedron-coordinated Mn ions but also tetrahedron-coordinated Co ions contribute to PMA. This work presents a guidance for tuning spin orientation by interface engineering.

Perpendicular magnetic anisotropy (PMA) of magnetic materials has received much attention because of its potential application to spintronics devices. In general, the tensely strained $(001)\text{\ensuremath{-}}\mathrm{L}{\mathrm{a}}_{2/3}\mathrm{S}{\mathrm{r}}_{1/3}\mathrm{Mn}{\mathrm{O}}_{3}$ (LSMO) layer is easy plane. Here we demonstrate that the tensile LSMO layer will exhibit an out-of-plane magnetic anisotropy if it is sandwiched between two $\mathrm{L}{\mathrm{a}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{r}}_{x}\mathrm{Co}{\mathrm{O}}_{2.5+\ensuremath{\delta}}$ (LSCO) layers. The most remarkable observation is that the PMA enhances with the increase of the Sr content in LSCO. It is $\ensuremath{\sim}2.7\ifmmode\times\else\texttimes\fi{}{10}^{6}\phantom{\rule{0.16em}{0ex}}\mathrm{erg}/\mathrm{c}{\mathrm{m}}^{3}$ for $x=0.05$ and $\ensuremath{\sim}4.3\ifmmode\times\else\texttimes\fi{}{10}^{6}\phantom{\rule{0.16em}{0ex}}\mathrm{erg}/\mathrm{c}{\mathrm{m}}^{3}$ for $x=0.5$. This value is two orders of magnitude greater than that obtained by compressively straining the LSMO film $(\ensuremath{\sim}{10}^{4}\phantom{\rule{0.16em}{0ex}}\mathrm{erg}/\mathrm{c}{\mathrm{m}}^{3})$. Analysis of high resolution lattice image shows the formation of perovskite/brownmillerite-type interfaces in the multilayers: Brownmillerite-like lattice structure forms in the interfacial layers of LSCO, resulting in a coherent tilting of adjacent $\mathrm{Mn}{\mathrm{O}}_{6}$ octahedra. This in turn leads to, as evidenced by the analysis of x-ray linear dichroism, selective orbital occupation thus spin reorientation. There is evidence that the brownmillerite-structured LSCO is more easily formed when $x$ is high, which explains the growth of anisotropy constant with the increase of Sr content.

Temperature and field induced magnetic phase transition in the magnetocaloric compound of ${\text{LaFe}}_{11.7}{\text{Si}}_{1.3}$ was investigated by means of M\"ossbauer spectroscopy and magnetization measurements. A coexistence of a magnetically split sextet and a paramagnetic doublet was observed in the temperature region of $\ensuremath{\sim}185\char21{}190\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ from zero-field M\"ossbauer spectra. A thermal hysteresis was verified between the heating and cooling processes that similar as observed in the thermomagnetic curves indicate that a first-order transition occurred in this compound. At the magnetic and paramagnetic phase coexisted region, the in-field M\"ossbauer measurements indicate that a span external fields from $\ensuremath{\sim}1$ to $\ensuremath{\sim}2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ induced a magnetic phase transition as the temperature induced transformation. The in-field M\"ossbauer spectroscopy confirms that the field-induced magnetic phase transition is first-order phase transition as temperature-induced transition occurred in ${\text{LaFe}}_{11.7}{\text{Si}}_{1.3}$.

A large magnetic entropy change \DeltaS\ has been observed in Heusler alloy Ni52.6Mn23.1Ga24.3 single crystal near the martensitic structural transition temperature of 300 K with applied field along [001] direction. The obtained \DeltaS\ under an applied field of 5 T reaches 18.0 J/Kg K (corresponding 146 mJ/cm(3) K). A more important result is that \DeltaS\ can achieve constant increase of 4.0 J/Kg K for the field increase of every tesla. The very large magnetic entropy change is attributed to the abrupt change of magnetization when the first-order martensitic-austensitic structural transition takes place. The phenomena of the large magnetic entropy change and the easy adjustment of the martensitic-austensitic transition-temperature indicate that the non-rare-earth based Ni-Mn-Ga single-crystal materials may have potential applications as magnetic refrigerants.

In this paper, we report the observation of large magnetic entropy change uDSu in La(Fe12xCox) 11.83Al1.17 (x 50.06,0.08) alloys. These alloys appear to be very attractive candidates for magnetic refrigerants near room temperature for the following advantages: ~a! showing a large magnetic entropy change uDSu, which is comparable with that of Gd; ~b! reversible in field and temperature; ~c! easily tunable TC near room temperature; and ~d! much cheaper raw materials ~even with relatively low purity! than the rare earth elements ~Gd, Dy!. Our experiments confirm that the sample LaFe11.83Al1.17 ( y50.91) shows antiferromagnetism, and further reveal that a small doping of Co can make its antiferromagnetic coupling collapse completely, resulting in a whole ferromagnetic state. The T C shifts to high temperature with the increase of Co doping. We chose samples of La(Fe12xCox) 11.83Al1.17 (x50.06,0.08) with TC around room temperature and found both of them show large mag