论文标题
带有面内磁场的二维两维半导体中的磁相变
Magnetic phase transitions in two-dimensional two-valley semiconductors with in-plane magnetic field
论文作者
论文摘要
两维电子气体（2DEG）在两谷半导体中具有两个离散的自由度，由旋转和山谷量子数给出。我们分析了具有SOI，平面磁场和电子电子相互作用的两谷半导体的零温度磁性不稳定性。施加的平面磁场和SOI的相互作用导致不同山谷中的非共线自旋量化。与交换间隔相互作用一起，这将产生一个丰富的相图，其中包含四个非平凡的磁相。对自由能的负非分析立方校正始终存在于2DEG中，这是一阶相变的原因。在这里，我们表明，阶参数的非零基态值可以降低该立方非分析性并驱动某些磁相变的二阶。我们还发现在零温度下的两个三临界点，它们与二阶相变的线一起构成了相图的量子关键扇区。相变可以通过静电门或平面磁场对外部进行调节。
A two-dimensional electron gas (2DEG) in two-valley semiconductors has two discrete degrees of freedom given by the spin and valley quantum numbers. We analyze the zero-temperature magnetic instabilities of two-valley semiconductors with SOI, in-plane magnetic field, and electron-electron interaction. The interplay of an applied in-plane magnetic field and the SOI results in non-collinear spin quantization in different valleys. Together with the exchange intervalley interaction this results in a rich phase diagram containing four non-trivial magnetic phases. The negative non-analytic cubic correction to the free energy, which is always present in an interacting 2DEG, is responsible for first order phase transitions. Here, we show that non-zero ground state values of the order parameters can cut this cubic non-analyticity and drive certain magnetic phase transitions second order. We also find two tri-critical points at zero temperature which together with the line of second order phase transitions constitute the quantum critical sector of the phase diagram. The phase transitions can be tuned externally by electrostatic gates or by the in-plane magnetic field.
