Quantum Disorder and Spin-Gaps In Models and Real Materials

University Of California-Davis, Davis CA

Investigators

Abstract

This grant has been awarded to support the work of Singh, a senior researcher/scholar at UC Davis. Singh has become well known for his work on frustrated magnets. Since the frustrated magnets do not order until very low temperatures, there are occasionally quantum effects in the phase transition. In this grant period he is planning to focus his research program in three parallel directions. In the first case, there will be a search for model spin systems, which undergo quantum phase transitions. In the second case, there will be calculations of a wide variety of experimentally measured quantities such as (not only) transport and thermodynamic responses, but also including neutron scattering cross sections and NMR relaxation rates. These will be compared with experiments on a variety of materials, such as high Tc superconductors, spin ladders and chains, 2-d spin gap systems, dimerized spin systems and other examples of complex and correlated electron effects. In the third case, there will be a continued search for controlled and systematic numerical methods for theoretical calculations. %%% This midcareer/senior PI is well known for his studies of materials which do not become magnetic until very low temperatures. The reason being that the atomic moments find themselves encouraged to point in different directions by other atomic moments in the environment. The magnets then, are called frustrated and their properties are strongly influenced by their inability to order. Furthermore they also become possible candidates for novel phenomena such as quantum phase transitions. The research program in this grant will pursue an organized course of research, including development of formalism, calculation of quantities which are measured in diverse experiments and then compared with experimental results and finally development of sophisticated tools of calculation. It is an ambitious and complex plan of research which is expected to provide insight into the properties of novel and complex materials. ***