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| VOLUME 103 (2016) | ISSUE 1 | PAGE 32 |
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Quasi-one-dimensional quantum spin liquid in the Cu(C4H4N2)(NO3)2 insulator
V. R. Shaginyan+*, V. A. Stephanovich× 1), K. G. Popov°, E. V. Kirichenko∇
+Konstantinov St. Petersburg Nuclear Physics Institute, National Research Centre "Kurchatov Institute", 188300 Gatchina, Russia *Clark Atlanta University, GA 30314 Atlanta, USA ×Institute of Physics, Opole University, 45-052 Opole, Poland °Komi Science Center UB of the RAS, 167982 Syktyvkar, Russia ∇Institute of Mathematics and Informatics, Opole University, 45-052 Opole, Poland
Abstract
We analyze measurements of the magnetization, differential susceptibility and specific heat of quasi-one dimensional insulator Cu(C4H4N2)(NO3)2 (CuPzN) subjected to magnetic fields. We show that the thermodynamic properties are defined by quantum spin liquid formed with spinons, with the magnetic field tuning the insulator CuPzN towards quantum critical point related to fermion condensation quantum phase transition (FCQPT) at which the spinon effective mass diverges kinematically. We show that the FCQPT concept permits to reveal and explain the scaling behavior of thermodynamic characteristics. For the first time, we construct the schematic T-H (temperature-magnetic field) phase diagram of CuPzN, that contains Landau-Fermi-liquid, crossover and non-Fermi liquid parts, thus resembling that of heavy-fermion compounds. |