Spin dynamics in pressure-induced magnetically ordered phases in(C4H12N2)Cu2Cl<

Abstract

We present inelastic neutron scattering experiments on the S = 1/2 frustrated gapped quantum magnet piperazinium hexachlorodicuprate (PHCC) under applied hydrostatic pressure. These results show that at 9 kbar the magnetic triplet excitations in the system are gapless, contrary to what was previously reported. Our results are in agreement with recent muon-spin relaxation experiments which found magnetic order above a quantum-critical point at 4.3 kbar. We show that the changes in the excitation spectrum can be primarily attributed to the change in a single exchange pathway.

High-pressure Raman study of the quantum magnet (C4H12N2)Cu2Bettler1, Simutis2, Perren3 et al. 2017Phys. Rev. BSelf Cite

“…This effect was not taken into account in Ref. 10. Unfortunately its magnitude for that particular experiment can not be assessed without additional in-situ pressure measurements using the same sample as in the original study.…”

Spin waves near the edge of halogen substitution induced magnetic order in Ni(Cl1−xBrx)2·4Mannig1, Povarov2, Ollivier3 et al. 2018Phys. Rev. BSelf Cite103191View full textAdd to dashboardCite

“…The best known examples in real materials are driven by applying hydrostatic pressure. Pressure induced ordering has been extensively studied the the dimer systems TlCuCl 3 [2][3][4] and PHCC [5][6][7], as well as in the single ion singlet compound CsFeCl 3 [8,9]. These transitions differ from the better known magnetic field induced "Bose-Einstein condensation of magnons" [10,11] in the same species [12][13][14].…”

Effect of disorder on a pressure-inducedz=1magnetic quantum phase transition

“…Subsequent muon-spin relaxation (μ + SR) experiments determined the presence of two distinct high-pressure magnetically ordered phases above a critical pressure p c ∼ 4.3 kbar [7]. The presence of a linearly dispersing gapless Goldstone mode at a pressure of 9(1) kbar was then confirmed by inelastic * manniga@ethz.ch † jmoeller@phys.ethz.ch ‡ http://www.neutron.ethz.ch/ neutron scattering experiments [8], and the application of pressure was shown to induce large changes in a single exchange pathway in the material leading to the closing of the gap at the QCP. In this paper, we use μ + SR to study the phase diagram of bond-disordered (C 4 H 12 N 2 )Cu 2 (Cl 1−x Br x ) 6 (PHCX) around this pressure-induced z = 1 QCP.…”

“…In these transitions, the spectrum is expected to be linear at the quantum-critical point, and hence z = 1. To date, the only known experimental realizations of such a pressure-induced QCP are TlCuCl 3 [3][4][5] and (C 4 H 12 N 2 )Cu 2 Cl 6 (PHCC) [6][7][8].…”

“…PHCC crystallizes in the triclinic space group P1 with lattice parameters a = 7.984(4)Å, b = 7.054(4)Å, c = 6.104(3)Å, α = 111.23 (8) • , β = 99.95 (9) • , and γ = 81.26(7)…”