Exchange Bias in a Layered Metal–Organic Topological Spin Glass

Abstract

<p class="first" id="d463577e292"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/108f4d5b-0a2f-4754-9c35-cc002a64c4b3/PubMedCentral/image/oc1c00568_0007"/> </div> </p><p id="d463577e294">The discovery of conductive and magnetic two-dimensional (2D) materials is critical for the development of next generation spintronics devices. Coordination chemistry in particular represents a highly versatile, though underutilized, route toward the synthesis of such materials with designer lattices. Here, we report the synthesis of a conductive, layered 2D metal–organic kagome lattice, Mn ₃(C ₆S ₆), using mild solution-phase chemistry. Strong geometric spin frustration in this system mediates spin freezing at low temperatures, which results in glassy magnetic dynamics consistent with a rare geometrically frustrated (topological) spin glass. Notably, we show that this geometric frustration engenders a large, tunable exchange bias of 1625 Oe in Mn ₃(C ₆S ₆), providing the first example of exchange bias in a coordination solid or a topological spin glass. Exchange bias is a critical component in a number of spintronics applications, but it is difficult to rationally tune, as it typically arises due to structural disorder. This work outlines a new strategy for engineering exchange bias systems using single-phase, crystalline lattices. More generally, these results demonstrate the potential utility of geometric frustration in the design of new nanoscale spintronic materials. </p><p class="first" id="d463577e316">Classic exchange bias relies on a disordered interface between a ferromagnet and antiferromagnet, impeding the design of next generation systems. We show that magnetic disorder due to <i>geometric</i> frustration engenders a large, tunable exchange bias in the metal−organic kagome lattice, Mn ₃(C ₆S ₆). As Mn ₃(C ₆S ₆) is a topological spin glass, the exchange bias may be a tuning handle for exotic nonequilibrium states. This work designates designer metal−organic lattices as a platform for novel emergent physical phenomena. </p>