Research: Dissipation induced magnetic order

In low dimensional quantum spin systems, the Mermin-Wagner theorem prohibits the formation of magnetic order because the continuous spin-rotational symmetry cannot be broken spontaneously. In this Letter, it was shown that a one-dimensional spin chain nevertheless can develop magnetic order for finite couplings to an environment, a situation which can for example occur if chains of magnetic atoms are deposited on a metallic substrate. This otherwise forbidden one dimensional magnetic order is possible because the conditions of the Mermin-Wagner theorem are invalid in the presence of the environment. This surprising result was obtained due to a novel quantum Monte Carlo method, which allows studying strongly interacting spin systems in the presence of dissipative environments.

M. Weber, D. J. Luitz, F. F. Assaad,
Dissipation-Induced Order: The S=1/2 Quantum Spin Chain Coupled to an Ohmic Bath,
Phys. Rev. Lett. 129, 056402 (2022) (arXiv)