Temperature effects in spin-dependent Hall currents in an ideal skyrmion gas
Temperature effects in spin-dependent Hall currents in an ideal skyrmion gas
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DOI：
10.1103/physrevb.103.184418
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发表时间：
2021-05
影响因子：
3.7
通讯作者：
Andrei Zadorozhnyi;Y. Dahnovsky
中科院分区：
文献类型：
--
作者：
Andrei Zadorozhnyi;Y. Dahnovsky
在经典和量子计算中寻找新的可靠和快速执行的逻辑和存储元件需要在新的量子材料中发现新的效应。Skyrmions是这样的磁性纹理，其中电子散射可以从本质上改变Skyrmion的形状和位置，Skyrmions可以用作存储元件，在经典计算中作为存储设备比磁区壁更有效。由于Skyrmion的运动即使对极小的电流也很敏感，因此我们研究了铁磁环境中理想Skyrmion气体中Skyrmion的电子散射。在这样的系统中，直流电和霍尔流变得与自旋有关。对于应用，重要的是考虑在整个温度范围内的霍尔效应，在假设天空存在的情况下。在这项研究中，我们发现了直接自旋电导的非单调温度依赖关系，即由于电子的自旋平行于铁磁矩而导致的电流沿外加电场的电导率。这种行为与传统的理解相矛盾，即温度只会增加电导率的值。对于小尺寸的天米子，自旋下降霍尔电导率表现出更显著的电导符号变化(即电流方向的变化)。所发现的效应强烈地依赖于费米能量。最显著的依赖关系发生在费米能量略低于和高于理想二维电子气的上(自旋向下)能带底部时。此外，我们还发现，直电阻率和霍尔电阻率分别与$2JG的交换积分$J$无关。
The quest for novel reliable and fast-performing logic and memory elements in classical and quantum computing requires discoveries of new effects in novel quantum materials. Skyrmions are such magnetic textures where electron scattering can essentially change the shape and location of the skyrmion, which can be used as a memory element being more efficient than domain walls as a memory device in classical computing. Because the skyrmion motion is sensitive even to very small currents, we study electron scattering by skyrmions in an ideal skyrmion gas in a ferromagnetic environment. In such systems, the direct and Hall currents become spin-dependent. For applications, it is important to consider a Hall effect in the whole range of temperatures under the assumption of the skyrmion existence. In this study, we find the nonmonotonic temperature dependence of the direct spin-up conductivity, i.e., the conductivity for the current directed along the applied electric field due to the electrons with the spin parallel to the ferromagnetic moment. Such a behavior contradicts the traditional understanding where the temperature only increases the value of the conductivity. The spin-down Hall conductivity is found to be even more dramatic exhibiting a conductivity sign change (i.e., a change in the current direction) with temperature for small skyrmion sizes. The found effects strongly depend on Fermi energy. The most pronounced dependencies take place if the Fermi energy is slightly below and above the bottom of the upper (spin-down) energy band of an ideal two-dimensional electron gas. In addition, we also find that the direct and Hall resistivities, ${\ensuremath{\rho}}_{xx}$ and ${\ensuremath{\rho}}_{xy}$, are independent of the exchange integral $J$ for $2Jg{\ensuremath{\varepsilon}}_{F}$.