Investigation of Quantum Matter by Quantum Point Magnetic Probes

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Quantum Matter is the kind of material where the quantum mechanical nature of electrons manifests itself explicitly in novel properties. It ranges from a spin frustrated magnetic system which realizes a peculiar ground state called spin liquid, to superconductivity where macroscopic electrical currents flow without resistance. The recent course of my research is not only to find the actual materials which may realize quantum mechanical ground states, but also to control them by external conditions, such as magnetic fields, to realize a new phase of matter. Another course of my research is to find the mutual interactions between the multiple degrees of freedom of electrons: spin, charge and the shape of the orbital where the electron resides. This research proposal focuses on five topics in quantum matter: (1) ground state properties of frustrated spin systems and the origin of new phases in magnetic fields, particularly in (a) geometrically frustrated spin system with/without spin-orbit couplings and (b) metallic chiral magnets; (2) effect of quenched disorder in frustrated magnets and dynamical spin correlations; (3) competing ground states and their control in superconducting systems; and (4) characterization of semiconductor-based quantum matter by quantum mechanical impurities. These research topics aim to discover a new class of materials which realizes the quantum states and/or new phases created by the external conditions. The result may elucidate the relation between the quantum states of electrons and the environmental parameters. The research method involves searching for new materials which may realize the quantum matter state, and characterizing those materials with the most sensitive magnetic probes: muons and lithium-8 nuclei, which are available at TRIUMF, Canada's accelerator research institute. The static and dynamical features of these materials may be investigated by this probe method and will be compared with the existing theories. The results will give feedback to the theoretical framework and/or the materials synthesis. Six undergraduate students and five PhD students will be trained to gain materials synthesis experience, basic characterization techniques, design of the hardware to make the measurements possible, in addition to the data analysis and theoretical calculations which simulate the materials in the computer. The publication of their results will train the presentation and communication skills of the highly qualified personnel (HQP), both to the general public and to the specialists in their research field. These skills will enable HQPs to be competitive for careers in academia and industry. This research will benefit Canada by pioneering quantum matter research and identification of new phases, which may lead to future applications.