INTRODUCTION OF LABORATORY

What happens when materials are cooled down close to absolute zero temperature? It sounds a boring question because everything freezes at T = 0. It is NOT, however, in some materials because quantum fluctuations persist even at absolute zero temperature. It was first discovered by Heike Kamerlingh Onnes at 1911, who was the first to liquify Helium and reach ~ 1 K, that the resistance of mercury suddenly vanished at low temperature. Followed by the discovery of the superconducting transition, many amazing quantum phenomena - superfluid transition of Helium, Bose-Einstein condensations of Alkali Bose gases - were found at low temperatures. We are interested in these quantum condensed states at low temperatures where the thermal fluctuation is negligible. Especially, we are now focusing on studies to characterize the elementary excitations of a new quantum condensed state of spins which may emerge in frustrated magnetic materials, such as antiferromagnets at two-dimensional triangular or kagome lattices, by precise themo-dynamic measurements at ultra-low temperatures.

MINORU YAMASHITA LAB. research

 

Our home-built ultralow temperature cryostat which allows us to perform various measurements down to ultralow temperatures (1 mK) under a strong magnetic field (13 T).

MINORU YAMASHITA LAB. research

 

Temperature dependence of the thermal Hall conductivity observed in kagome antiferromagnet Cd-kapellasite. Although this material is a blue transparent insulator, the trajectory of the thermal current is bent under the magnetic field.

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EXPLORING SOMETHING UNKNOWN IS ALWAYS EXCITING. JOIN OUR CHALLENGES FOR MYSTERIES HIDING IN NEW MATERIALS UNDER UNPRECEDENTED EXTREME ENVIRONMENTS.

We are studying exotic phenomena at very low temperatures. Helium, for example, never freezes but remains liquid even at absolute zero temperature. Liquid Helium undergoes a superfluid transition at ~2 K and shows bizarre phenomena below the transition temperature - a flow without viscosity, a creeping climbing along container walls, etc. These phenomena are well known examples of macroscopic manifestations of the quantum mechanics which describes phenomena at microscopic length scales. Macroscopic quantum states provide us clear cuts to understand quantum physics which often defies our intuitive understandings of Nature. Condensed-matter physics at very low temperatures are good playgrounds to study these macroscopic quantum phenomena, and are our main research fields. In particular, when a trivial stable state is frustrated by quantum fluctuations, new non-trivial states emerge. We are now exploring these exotic states of new materials down to very low temperatures.

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