Unconventional field induced phases in a quantum magnet formed by free radical tetramers

Andrés Saúl (1) , Nicolas Gauthier , Reza Moosavi Askari , Michel Côté (2) , Thierry Maris (3) , Christian Reber (4) , Anthony Lannes (5) , Dominique Luneau (5) , Michael Nicklas , Joseph M Law , Elizabeth Lauren Green , Jochen Wosnitza , Andrea Bianchi (6) , Adrian Feiguin (7)

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
2 Département de Physique [Montréal]
3 Inorganic Chemistry Laboratory-Faculty of Chemistry
4 UdeM - Université de Montréal
5 LMI - Laboratoire des Multimatériaux et Interfaces
6 CRMSB - Centre de résonance magnétique des systèmes biologiques
7 Department of Physics, Northeastern University

We report experimental and theoretical studies on the magnetic and thermodynamic properties of NIT-2Py, a free radical based organic magnet. From magnetization and specific-heat measurements we establish the temperature versus magnetic field phase diagram which includes two Bose-Einstein condensates (BEC) and an infrequent half-magnetization plateau. Calculations based on density functional theory demonstrate that magnetically this system can be mapped to a quasi-two-dimensional structure of weakly coupled tetramers. Density matrix renormalization group calculations show the unusual characteristics of the BECs where the spins forming the low-field condensate are different than those participating in the high-field one.

Domaines: Matière Condensée [cond-mat]

Andrés Saúl, Nicolas Gauthier, Reza Moosavi Askari, Michel Côté, Thierry Maris, et al.. Unconventional field induced phases in a quantum magnet formed by free radical tetramers. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2018, 97 (6), ⟨10.1103/physrevb.97.064414⟩. ⟨hal-01970669⟩