Quantum Disorder and Spin-Gaps In Models and Real Materials

这笔赠款已被授予支持辛格，在加州大学戴维斯分校的高级研究员/学者的工作。 辛格因其在受挫折的磁铁方面的工作而闻名。 由于受抑磁体直到非常低的温度才有序，所以在相变中偶尔会有量子效应。 在此期间，他计划将他的研究计划集中在三个平行的方向。 在第一种情况下，将有一个模型自旋系统，经历量子相变的搜索。 在第二种情况下，将有各种各样的实验测量的量，如（不仅）运输和热力学响应，但也包括中子散射截面和NMR弛豫率的计算。 这些将与各种材料，如高Tc超导体，自旋梯和链，2-D自旋间隙系统，二聚自旋系统和其他例子的复杂和相关的电子效应的实验进行比较。在第三种情况下，将继续寻找理论计算的受控和系统的数值方法。%这位职业生涯中期/高级PI以其对材料的研究而闻名，这些材料直到非常低的温度才变得有磁性。 原因是原子的磁矩发现自己被环境中的其他原子磁矩鼓励指向不同的方向。 然后，磁铁，被称为挫折和他们的性质受到强烈影响，他们无法秩序。 此外，它们也成为量子相变等新现象的可能候选者。 该研究计划将追求有组织的研究过程，包括形式主义的发展，在各种实验中测量的数量的计算，然后与实验结果进行比较，最后开发复杂的计算工具。 这是一项雄心勃勃而复杂的研究计划，预计将深入了解新型和复杂材料的特性。

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.***