Very Low Temperature Physics
Roman Movshovich - Capability Leader
Our interests lie in the frontier areas of the correlated electron physics, including unconventional superconductivity, Ce, Yb, and U-based based heavy fermion materials, quantum criticality, and many surprises that the goddess of serendipity may bring our way while we are investigating novel materials for the first time. We perform thermodynamic (specific heat, magnetization, susceptibility) and transport (electric and thermal conductivity) measurements, occasionally under pressure of up to 2 GPa, magnetic fields of up to 14 T, in dilution refrigerators (we have two) down to 20 mK. There are several upgrades on the way, both for more powerful dilution refrigerator on one system (with a rotator capability and a gradient field) and a magnet (14 T from 9 T) on another.
A number of brilliant postdocs have pushed research in our VLT group in a number of interesting directions, participated in new discoveries, and developed new capabilities. They are Marcelo Jaime, Andrea Bianchi, Cigdem Capan, Filip Ronning, and Yoshifumi Tokiwa and Corneliu Miclea. Current research is centered on the so-called 115 family of heavy fermion compounds. The Ce-based members of this family, CeCoIn5, CeIrIn5, and CeRhIn5, display an uncommonly rich phenomena, including unconventional superconductivity, Quantum Critical Points, coexistence of superconductivity and magnetism, competition of the same, etc. The pressure-magnetic field-temperature phase diagrams of these compounds are rich and complicated. Of particular interest to our group is the high field – low temperature (LTHF) superconducting phase, which exists inside the superconducting phase of CeCoIn5 below 300 mK and between 10 T and critical field of 12 T. It was originally suggested as a realization of the spatially inhomogeneous Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) superconducting phase, predicted theoretically in early 1960’s. The LTHF phase in CeCoIn5 still refuses to unveil its precise nature, in spite of the world–wide efforts since it was discovered in our group in 2003. A variety of bulk and microscopic measurements are on the way in our laboratory as well to solve this intriguing problem.
Specific heat of CeCoIn5 versus temperature and magnetic field. The red ridge in the low temperature - high field corner within the superconducting phase identifies the phase transition into purported FFLO phase.
National High Magnetic Field Laboratory/NHMFL
Low Energy Spectroscopy