The Eminuscent Phase in Geometrically Frustrated Magnets - a challenge to quantum spin liquids

Some geometrically frustrated magnets are claimed to host a quantum spin liquid (QSL) state. The QSL is a theoretically-proposed many-body state that is fully quantum coherent and, if achievable, may offer a new route to quantum computation. We show that the response of such materials to small amounts of disorder cannot be explained in terms of the canonical source-field construct and suggests a temperature-dependent permeability with a hidden energy scale where short-range order among spins is established. This particular type of short range order mediates long range interactions and is called the eminuscent phase, best described within the Coulomb representation. The instability of the eminuscent phase to spin glass formation in 3D and random singlets in 2D, in addition to the short range order itself, pose serious challenges to the viability of the QSL state. We will also discuss ways to study this unique phase of magnetism.