Diagnosis of quantum criticality by nuclear spin-echo decay method

• Published in: Physica status solidi. B. Basic research 2010-03, Vol.247 (3), p.520-524
• Main Authors: Kambe, S., Sakai, H., Tokunaga, Y., Chudo, H., Walstedt, R. E.
• Format: Article
• Language: English
• Subjects: 74.25.Nf; 74.40.+k; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Heavy-fermion superconductors; Magnetic properties; Physics; Properties of type I and type II superconductors; Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.); Superconducting materials (excluding high-tc compounds); Superconductivity
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200983063

The Gaussian spin–spin relaxation time T2G, as determined by nuclear magnetic resonance (NMR) spin‐echo decay measurements, is found to be useful for diagnosis of quantum critical behaviour in heavy‐fermion systems. Combining T2G with the spin–lattice relaxation time T1, the exponent ϕ of the quantity $T_1 T/T_{2G}^2 \sim T^\phi$ is predicted to be sensitive to the type of quantum criticality in the system concerned. In fact, in the heavy‐fermion system USn3 near the quantum critical point, $T_1 T/T_{2G}^2$ is found to be constant, as expected for a 3D‐SDW magnetic instability.