Quantum critical transition amplifies magnetoelastic coupling in Mn[N(CN)2]2
T. V. Brinzari, P. Chen, Q.-C. Sun, J. Liu, L.-C. Tung, Y. Wang, J. A. Schlueter, J. Singleton, J. L. Manson, M.-H. Whangbo, A. P. Litvinchuk, and J. L. Musfeldt
Accepted
We report the discovery of a magnetic quantum critical transition in Mn[N(CN)$_2$]$_2$ that drives the system from a canted antiferromagnetic state to the fully polarized state with amplified magnetoelastic coupling as an intrinsic part of the process. The local lattice distortions, revealed through systematic phonon frequency shifts, suggest a combined MnN$_6$ octahedra distortion + counter-rotation mechanism that reduces antiferromagnetic interactions and acts to accommodate the field-induced state. These findings deepen our understanding of magnetoelastic coupling near a magnetic quantum critical point and away from the static limit.