Quantum critical fluctuations in layered YFe 2 Al 10

Significance Temperature-driven phase transitions, such as the melting of ice or the boiling of water, are a familiar part of daily life. Much less is known about the most extreme phase transitions, which happen only at zero temperature, where quantum fluctuations limit the stabilities of different collective ground states such as magnetic order and superconductivity. We report an experimental investigation of YFe2 Al10 , where planes of Fe atoms are naturally poised on the verge of ferromagnetic order, exactly atT = 0. The thermal, magnetic, and electrical transport properties in YFe2 Al10 all diverge asT → 0, a process that can be reversed by magnetic fields in a way that is dictated by the underlying system energy.