Universal behaviors of magnon-mediated spin transport in disordered nonmagnetic metalferromagnetic insulator heterostructures

We numerically investigate magnon-mediated spin transport through nonmagnetic metal/ferromagnetic insulator(NM/FI)heterostructures in the presence of Anderson disorder,and discover universal behaviors of the spin conductance in both one-dimensional(1D)and 2D systems.In the localized regime,the variance of logarithmic spin conductanceσ2(lnGγ)shows a universal linear scaling with its average(lnGγ),independent of Fermi energy,temperature,and system size in both 1D and 2D cases.In 2D,the competition between disorder-enhanced density of states at the NM/FI interface and disorder-suppressed spin transport leads to a non-monotonic dependence of average spin conductance on the disorder strength.As a result,in the metallic regime,average spin conductance is enhanced by disorder,and a new linear scaling between spin conductance fluctuation rms(GT)and average spin conductance GT is revealed which is universal at large system width.These universal scaling behaviors suggest that spin transport mediated by magnon in disordered 2D NM/FI systems belongs to a new universality class,different from that of charge conductance in 2D normal metal systems.

Multiple magnetic transitions and magnetocaloric effect of Tb_(4)Coln alloy

We report on the magnetic,magnetocaloric,thermal,and electrical transport properties of Tb_(4)Coln alloy,which crystallizes in two phases,Tb_6Co_(2.1)In_(0.8)(space group Immm)and Tb_(2)In_(0.9)Co_(0.1)(space group P6_(3)/mmc),respectively.The alloy reveals three successive magnetic transitions around T_(1)(163 K),T_(2)(50 K),and T_(3)(29 K),respectively,associated with paramagnetic to ferromagnetic transition and two sequential antiferromagnetic transitions.The low-temperature transition T_(3) follows the first-order magnetic behavior and exhibits the field-induced magnetic transition.Meanwhile,T_(2) and T_(1) are found to be second-order in nature which opens a possibility for hysteresis-free magnetocaloric application.The magnetocaloric properties are determined using different magnetocaloric figures of merits such as-ΔS_(M),ΔT_(ad).RCP,and TEC(10).Additionally,the universal curve behavior in the isothermal entropy change unveils the variation in critical exponents around T_(1) and T_(2) due to the magnetic inhomogeneity in the alloy.Besides,the electrical transport properties of the metallic alloy denote the maximum magnetoresistance of-10%around T_(1).