ISSP - The institute for Solid State Physics

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Sakakibara Group

Research Associate

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Magnetic phenomena in condensed matter can be observed at a wide range of temperatures. In heavy fermions and certain other systems, interesting magnetic behavior often occurs at low temperatures much below 1 K. Because of difficulty in making magnetic measurements at such low temperatures, little work has been done to date. Our interest is to research those magnetic materials having low characteristic temperatures, such as f-electron compounds, heavy fermions, quantum spin systems, and geometrically frustrated spin systems. To study these systems, we also develop necessary equipment. Equipment we have successfully developed includes: high sensitivity magnetometers which are operable even at extremely low temperatures down to the lowest of 30 mK, and equipment to perform angle-resolved specific heat measurements in a rotating magnetic field. The latter is an effective tool for investigating the nodal structures of anisotropic superconductors.

The polar-angle (θ) variation of the heat capacity divided by temperature, C/T, of the heavy-fermion superconductor UPd2Al3 (Tc = 2.0 K) obtained in various magnetic fields rotated in the ac plane of the hexagonal crystal. (a) The experimental results obtained at T = 0.2 K. (b) Calculated results of the field-angular variation of the zero-energy density of states, assuming a horizontal line node. The calculated results reproduce the experimental data satisfactorily. The angular variation of C/T of UPd2Al3 strongly suggests the existence of a horizontal line node in the superconducting gap.

Research Subjects

  1. Magnetism and superconductivity in heavy electron systems
  2. Multipole orderings and fluctuations in f electron systems
  3. Magnetization of geometrically frustrated magnets
  4. Ground state properties of quantum spin systems