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Title: Giant suppression of phononic heat transport in a quantum magnet BiCu 2PO 6

Thermal transport of quantum magnets has elucidated the nature of low energy elementary excitations and complex interplay between those excited states via strong scattering of thermal carriers. BiCu 2PO 6 is a unique frustrated spin-ladder compound exhibiting highly anisotropic spin excitations that contain both itinerant and localized dispersion characters along the b- and a-axes respectively. Here, we investigate thermal conductivity κ of BiCu 2PO 6 under high magnetic fields (H) of up to 30 tesla. A dip-feature in κ, located at ~15K at zero-H along all crystallographic directions, moves gradually toward lower temperature (T) with increasing H, thus resulting in giant suppression by a factor of ~30 near the critical magnetic field of H c≅23.5 tesla. The giant H- and T-dependent suppression of κ can be explained by the combined result of resonant scattering of phononic heat carriers with magnetic energy levels and increased phonon scattering due to enhanced spin fluctuation at H c, unequivocally revealing the existence of strong spin-phonon coupling. Moreover, we find an experimental indication that the remaining magnetic heat transport along the b-axis becomes almost gapless at the magnetic quantum critical point realized at H c.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [2] ;  [1]
  1. Seoul National Univ. (Korea, Republic of)
  2. National Taiwan Univ., Taipei (Taiwan)
  3. Florida State Univ., Tallahassee, FL (United States)
  4. Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea, Republic of)
  5. Inst. for Basic Science (IBS), Seoul (Korea, Republic of); Seoul National Univ. (Korea, Republic of)
Publication Date:
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab.
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1378576