by Hester, Gavin, Nair, H. S., Reeder, T., Yahne, D. R., DeLazzer, T. N., Berges, L., Ziat, D., Neilson, J. R., Aczel, A. A., Sala, G., Quilliam, J. A. and Ross, K. A.
Abstract:
The quantum dimer magnet (QDM) is the canonical example of quantum magnetism. The QDM state consists of entangled nearest-neighbor spin dimers and often exhibits a field-induced triplon Bose-Einstein condensate (BEC) phase. We report on a new QDM in the strongly spin-orbit coupled, distorted honeycomb-lattice material Yb2Si2O7. Our single crystal neutron scattering, specific heat, and ultrasound velocity measurements reveal a gapped singlet ground state at zero field with sharp, dispersive excitations. We find a field-induced magnetically ordered phase reminiscent of a BEC phase, with exceptionally low critical fields of H-c1 similar to 0.4 and H-c2 similar to 1.4 T. Using inelastic neutron scattering in an applied magnetic field we observe a Goldstone mode (gapless to within delta E = 0.037 meV) that persists throughout the entire field-induced magnetically ordered phase, suggestive of the spontaneous breaking of U(1) symmetry expected for a triplon BEC. However, in contrast to other well-known cases of this phase, the high-field (mu H-0 >= 1.2 T) part of the phase diagram in Yb2Si2O7 is interrupted by an unusual regime signaled by a change in the field dependence of the ultrasound velocity and magnetization, as well as the disappearance of a sharp anomaly in the specific heat. These measurements raise the question of how anisotropy in strongly spin-orbit coupled materials modifies the field induced phases of QDMs.
Reference:
Hester, Gavin, Nair, H. S., Reeder, T., Yahne, D. R., DeLazzer, T. N., Berges, L., Ziat, D., Neilson, J. R., Aczel, A. A., Sala, G., Quilliam, J. A. and Ross, K. A., "Novel Strongly Spin-Orbit Coupled Quantum Dimer Magnet: Yb2Si2O7", In PHYSICAL REVIEW LETTERS, vol. 123, no. 2, 2019.
Bibtex Entry:
@article{ WOS:000474894200024,
Author = {Hester, Gavin and Nair, H. S. and Reeder, T. and Yahne, D. R. and
DeLazzer, T. N. and Berges, L. and Ziat, D. and Neilson, J. R. and
Aczel, A. A. and Sala, G. and Quilliam, J. A. and Ross, K. A.},
Title = {Novel Strongly Spin-Orbit Coupled Quantum Dimer Magnet: Yb2Si2O7},
Journal = {PHYSICAL REVIEW LETTERS},
Year = {2019},
Volume = {123},
Number = {2},
Month = {JUL 9},
Abstract = {The quantum dimer magnet (QDM) is the canonical example of quantum
magnetism. The QDM state consists of entangled nearest-neighbor spin
dimers and often exhibits a field-induced triplon Bose-Einstein
condensate (BEC) phase. We report on a new QDM in the strongly
spin-orbit coupled, distorted honeycomb-lattice material Yb2Si2O7. Our
single crystal neutron scattering, specific heat, and ultrasound
velocity measurements reveal a gapped singlet ground state at zero field
with sharp, dispersive excitations. We find a field-induced magnetically
ordered phase reminiscent of a BEC phase, with exceptionally low
critical fields of H-c1 similar to 0.4 and H-c2 similar to 1.4 T. Using
inelastic neutron scattering in an applied magnetic field we observe a
Goldstone mode (gapless to within delta E = 0.037 meV) that persists
throughout the entire field-induced magnetically ordered phase,
suggestive of the spontaneous breaking of U(1) symmetry expected for a
triplon BEC. However, in contrast to other well-known cases of this
phase, the high-field (mu H-0 >= 1.2 T) part of the phase diagram in
Yb2Si2O7 is interrupted by an unusual regime signaled by a change in the
field dependence of the ultrasound velocity and magnetization, as well
as the disappearance of a sharp anomaly in the specific heat. These
measurements raise the question of how anisotropy in strongly spin-orbit
coupled materials modifies the field induced phases of QDMs.},
DOI = {10.1103/PhysRevLett.123.027201},
Article-Number = {027201},
ISSN = {0031-9007},
EISSN = {1079-7114},
ResearcherID-Numbers = {Sala, Gabriele/W-2778-2018
Aczel, Adam/A-6247-2016
Nair, Hari/D-3069-2013},
ORCID-Numbers = {Sala, Gabriele/0000-0002-6654-0275
Aczel, Adam/0000-0003-1964-1943
Neilson, James/0000-0001-9282-5752
Nair, Hari/0000-0002-4301-9380},
Unique-ID = {WOS:000474894200024},
}