Circular currents in an antiferromagnetic ring with a side-coupled one-dimensional chain

Abstract: We investigate persistent charge and spin currents in an antiferromagnetic (AFM) quantum ring threaded by an Aharonov-Bohm flux, in the presence of a side-coupled one-dimensional non-magnetic (NM) chain. In the absence of the chain, the spin circular current vanishes exactly due to the symmetry between the up and down spin sub-Hamiltonians. Modeling the system within a tight-binding (TB) framework, we compute the currents using a second-quantized approach. Both charge and spin currents can be selectively tuned by adjusting the ring-chain coupling strength. Temperature plays a crucial role in modulating the currents, and interestingly, we find that they increase significantly with rising temperature--contrary to conventional expectations.