# Condensed Matter Physics Seminar

Monday, October 14, 2013
4:00pm to 5:00pm
In this talk, I will show how the recent observation of heavy Ising quasiparticles in the hidden order phase provides the missing puzzle piece. To form Ising quasiparticles, the conduction electrons must hybridize with a local Ising moment - a 5f2 state of the uranium atom with integer spin. As the hybridization mixes states of integer and half-integer spin, it is itself a spinor and this hastatic'' (hasta: [Latin] spear) order parameter therefore breaks both time-reversal and double time-reversal symmetries. A microscopic theory of hastatic order naturally unites a number of disparate experimental results from the large entropy of condensation to the spin rotational symmetry breaking seen in torque magnetometry. Hastatic order also has a number of experimental consequences, most notably a tiny transverse magnetic moment in the conduction electrons.