TY - JOUR
T1 - Gapless dynamic magnetic ground state in the charge-gapped trimer iridate Ba4NbIr3 O12
AU - Bandyopadhyay, Abhisek
AU - Lee, S.
AU - Adroja, D. T.
AU - Lees, M. R.
AU - Stenning, G. B.G.
AU - Aich, P.
AU - Tortora, Luca
AU - Meneghini, C.
AU - Cibin, G.
AU - Berlie, Adam
AU - Saha, R. A.
AU - Takegami, D.
AU - Meléndez-Sans, A.
AU - Poelchen, G.
AU - Yoshimura, M.
AU - Tsuei, K. D.
AU - Hu, Z.
AU - Chan, Ting Shan
AU - Chattopadhyay, S.
AU - Thakur, G. S.
AU - Choi, Kwang Yong
N1 - Publisher Copyright:
© 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
PY - 2024/7
Y1 - 2024/7
N2 - We present an experimental investigation of the magnetic ground state in Ba4NbIr3O12, a fractional valent trimer iridate. X-ray absorption and photoemission spectroscopy show that the Ir valence lies between 3+ and 4+ while Nb is pentavalent. Combined dc/ac magnetization, specific heat, and muon spin rotation/relaxation (μSR) measurements reveal no magnetic phase transition down to 0.05 K. Despite a significant Weiss temperature (ΘW∼-15 to -25 K) indicating antiferromagnetic correlations, a quantum spin-liquid (QSL) phase emerges and persists down to 0.1 K. This state likely arises from geometric frustration in the edge-sharing equilateral triangle Ir network. Our μSR analysis reveals a two-component depolarization, arising from the coexistence of rapidly (90%) and slowly (10%) fluctuating Ir moments. Powder x-ray diffraction and Ir-L3edge x-ray absorption fine structure spectroscopy identify 8-10% Nb/Ir site-exchange, reducing frustration within part of the Ir network, and likely leading to the faster muon spin relaxation, while the structurally ordered Ir ions remain highly geometrically frustrated, giving rise to the rapidly spin-fluctuating QSL ground state. At low temperatures, the magnetic specific heat varies as γT+αT2, indicating gapless spinon excitations, and possible Dirac QSL features with linear spinon dispersion, respectively.
AB - We present an experimental investigation of the magnetic ground state in Ba4NbIr3O12, a fractional valent trimer iridate. X-ray absorption and photoemission spectroscopy show that the Ir valence lies between 3+ and 4+ while Nb is pentavalent. Combined dc/ac magnetization, specific heat, and muon spin rotation/relaxation (μSR) measurements reveal no magnetic phase transition down to 0.05 K. Despite a significant Weiss temperature (ΘW∼-15 to -25 K) indicating antiferromagnetic correlations, a quantum spin-liquid (QSL) phase emerges and persists down to 0.1 K. This state likely arises from geometric frustration in the edge-sharing equilateral triangle Ir network. Our μSR analysis reveals a two-component depolarization, arising from the coexistence of rapidly (90%) and slowly (10%) fluctuating Ir moments. Powder x-ray diffraction and Ir-L3edge x-ray absorption fine structure spectroscopy identify 8-10% Nb/Ir site-exchange, reducing frustration within part of the Ir network, and likely leading to the faster muon spin relaxation, while the structurally ordered Ir ions remain highly geometrically frustrated, giving rise to the rapidly spin-fluctuating QSL ground state. At low temperatures, the magnetic specific heat varies as γT+αT2, indicating gapless spinon excitations, and possible Dirac QSL features with linear spinon dispersion, respectively.
UR - http://www.scopus.com/inward/record.url?scp=85198752958&partnerID=8YFLogxK
U2 - 10.1103/PhysRevMaterials.8.074405
DO - 10.1103/PhysRevMaterials.8.074405
M3 - Article
AN - SCOPUS:85198752958
SN - 2475-9953
VL - 8
JO - Physical Review Materials
JF - Physical Review Materials
IS - 7
M1 - 074405
ER -