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

TL;DR

This study explores the magnetic phases of the organic magnet NIT-2Py, revealing unconventional field-induced phases including two Bose-Einstein condensates and a rare half magnetization plateau through experimental and theoretical methods.

Contribution

It provides the first detailed phase diagram of NIT-2Py, combining experimental data with theoretical modeling to uncover unique quantum magnetic phenomena.

Findings

Identification of two distinct Bose-Einstein condensates in NIT-2Py

Observation of a half magnetization plateau in the phase diagram

Theoretical mapping to a quasi-two-dimensional tetramer structure

Abstract

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 demonstrates 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.