Quantum field theory of metallic spin glasses.

We introduce an effective field theory for the vicinity of a zero temperature quantum transition between a metallic spin glass (“spin density glass”) and a metallic quantum paramagnet. Following a mean field analysis, we perform a perturbative renormalization-group study and find that the critical properties are dominated by static disorder-induced fluctuations, and that dynamic quantum-mechanical effects are dangerously irrelevant. A Gaussian fixed point is stable for a finite range of couplings for spatial dimensionality d > 8, but disorder effects always lead to runaway flows to strong coupling for d ≤ 8. Scaling hypotheses for a static strong-coupling critical field theory are proposed. The non-linear susceptibility has an anomalously weak singularity at such a critical point. Although motivated by a perturbative study of metallic spin glasses, the scaling hypotheses are more general, and could apply to other quantum spin glass to paramagnet transitions. Typeset using REVTEX