Magnetic field induced transitions from spin glass to liquid to long rangeorder in a 3D geometrically frustrated magnet

Gadolinium gallium garnet, Gd3Ga5O12, has an extraordinary low temperature phase diagram including a spin glass phase near H = O T, an antiferromagnet ic (AFM) phase for 0.7 less than or equal to H less than or equal to 1.4 T, and, at intermediate fields, an apparent spin-liquid state without long ra nge order. We have characterized the intermediate field (IF) state through heat capacity, thermal conductivity, and magnetocaloric measurements. Our r esults indicate that the IF phase is distinct from the spin glass, and that the phase boundary between the AFM and IF phases has a distinct minimum at T similar to 0.18 K, in analogy to the minimum in the melting curve of He- 4.