Sun Zhiyuan, Kaneko Tatsuya, Golež Denis, Millis Andrew J
Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027, USA.
Center for Computational Quantum Physics, Flatiron Institute, 162 5th Avenue, New York, New York 10010, USA.
Phys Rev Lett. 2021 Sep 17;127(12):127702. doi: 10.1103/PhysRevLett.127.127702.
We show that in electron-hole bilayers with excitonic orders arising from conduction and valence bands formed by atomic orbitals that have different parities, nonzero interlayer tunneling leads to a second-order Josephson effect. This means the interlayer electrical current is related to the phase of the excitonic order parameter as J=J_{c}sin2θ instead of J=J_{c}sinθ and that the system has two degenerate ground states at θ=0,π that can be switched by an interlayer voltage pulse. When generalized to a three dimensional stack of alternating electron-hole planes or a two dimensional stack of chains, the ac Josephson effect implies that electric field pulses perpendicular to the layers and chains can steer the order parameter phase between the two degenerate ground states, making these devices ultrafast memories. The order parameter steering also applies to the excitonic insulator candidate Ta_{2}NiSe_{5}.
我们表明，在具有由具有不同宇称的原子轨道形成的导带和价带产生的激子序的电子 - 空穴双层中，非零层间隧穿会导致二阶约瑟夫森效应。这意味着层间电流与激子序参量的相位相关，即(J = J_{c}\sin2\theta)，而不是(J = J_{c}\sin\theta)，并且该系统在(\theta = 0,\pi)处有两个简并基态，可通过层间电压脉冲进行切换。当推广到交替电子 - 空穴平面的三维堆叠或链的二维堆叠时，交流约瑟夫森效应意味着垂直于层和链的电场脉冲可以在两个简并基态之间操纵序参量相位，使这些器件成为超快存储器。序参量操纵也适用于激子绝缘体候选物(Ta_{2}NiSe_{5})。
