77 research outputs found
Giant coercivity, resistivity upturn, and anomalous Hall effect in ferrimagnetic FeTb
Despite the blooming interest, the transition-metal rare-earth ferrimagnets
have not been comprehensively understood in terms of their coercivity and
transport properties. Here, we report a systematic study of the magnetic and
transport properties of ferrimagnetic FeTb alloy by varying the layer thickness
and temperature. The FeTb is tuned from the Tb-dominated regime to the
Fe-dominated regime via the layer thickness, without varying the composition.
The coercivity closely follows the scaling (where
is the polar angle of the external magnetic field) and increases
quasi-exponentially upon cooling (exceeding 90 kOe at low temperatures),
revealing that the nature of the coercivity is the thermally-assisted domain
wall depinning field. The resistivity exhibits a quasi-linear upturn upon
cooling possibly due to thermal vibrations of the structure factor of the
amorphous alloy. The existing scaling laws of the anomalous Hall effect in the
literature break down for the amorphous FeTb that are either Fe- or
Tb-dominated. These findings should advance the understanding of the
transition-metal-rare-earth ferrimagnets and the associated ferrimagnetic
phenomena in spintronics.Comment: In press at Phys. Rev.
Interfacial Dzyaloshinskii-Moriya interaction and spin-orbit torque in Au1-xPtx/Co bilayers with varying interfacial spin-orbit coupling
The quantitative roles of the interfacial spin-orbit coupling (SOC) in
Dzyaloshinskii-Moriya interaction (DMI) and dampinglike spin-orbit torque
({\tau}DL) have remained unsettled after a decade of intensive study. Here, we
report a conclusive experiment evidence that, because of the critical role of
the interfacial orbital hybridization, the interfacial DMI is not necessarily a
linear function of the interfacial SOC, e.g. at Au1-xPtx/Co interfaces where
the interfacial SOC can be tuned significantly via strongly composition
(x)-dependent spin-orbit proximity effect without varying the bulk SOC and the
electronegativity of the Au1-xPtx layer. We also find that {\tau}DL in the
Au1-xPtx/Co bilayers varies distinctly from the interfacial SOC as a function
of x, indicating no important {\tau}DL contribution from the interfacial
Rashba-Edelstein effect
Modelling the thermal-hydro-mechanical behaviour of unsaturated soils with a high degree of saturation using extended precise integration method
Unsaturated soils with a high degree of saturation (HDS) are commonly encountered in marine and lacustrine sediments. In these soils, the gas phase generally exists in the state of discrete bubbles, which is sensitive to stress and temperature changes and can dramatically change the soil’s engineering properties. This paper explores the thermal-induced behaviour of HDS soils using an efficient extended precise integration method (XPIM). Biot poroelasticity theory, extended to include thermal effects and compressibility of gas-water mixture, is employed to analyze the soil behaviour under non-isothermal condition. Based on Laplace-Fourier transform and Taylor series expansion, such problems can be solved by XPIM. The robustness of XPIM was confirmed by comparing the present results with analytical solutions and test data. Extensive parametric studies are undertaken to examine both the effects of soil grain thermal expansion and anisotropic permeability on soil behaviour, and temperature effects on degree of saturation (Sr). The thermal-induced variations in Sr are more pronounced with lower initial values (e.g. 90% compared to 99%). These quantitative results demonstrate the benefits of the proposed method, which proves to be extremely efficient and several orders more precise than conventional numerical approaches, with its precision limited only by the computational effort used
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