Abstract
A two-dimensional electron system in the presence of a magnetic field and microwave irradiation can undergo a phase transition towards a zero-resistance state (ZRS). A widely used model predicts the ZRS to be a domain state, which responds to applied dc voltages or dc currents by slightly changing the domain structure. Here we propose an alternative response scenario, according to which the domain pattern remains unchanged. Surprisingly, a fixed domain pattern does not destroy zero-resistance, provided that the resistance is direction independent. Otherwise, if the symmetry of the domain pattern allows a direction dependence of the resistance, the domain state can be dissipative. We give examples for both situations and simulate the response behavior numerically.
Highlights
At the beginning of this century, Mani et al [1] and Zudov et al [2] discovered a new dissipationless state of a 2D electron gas that is exposed to microwave irradiation and an out-of-plane magnetic field [3]
Our main conclusion from this is that the application of an external field E e0 on a domain state with e(r) = e0(r) will lead to small changes of the local electric field, which scale with E
We have considered the response of domain states to external fields that are much smaller the internal fields within the domains
Summary
At the beginning of this century, Mani et al [1] and Zudov et al [2] discovered a new dissipationless state of a 2D electron gas that is exposed to microwave irradiation and an out-of-plane magnetic field [3]. An in turn different group of theoretical models instead predicts that the ZRS is an inhomogeneous domain state. Seems to imply a negative-resistance state instead of a ZRS This is only true if the system is assumed to be homogeneous and the effect of boundaries and contacts can be neglected. A different ansatz is to allow for an inhomogeneous charge distribution In this case, neglecting boundary and contact effects, a conventional linear-response experiment measures the effective conductivity Σ, which determines the linear relation. This microscopically different mechanism results in a different effective conductivity, the determination of which turns out to be more difficult in the domain-wall scenario.
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