Gapped Spin Excitation in Magnetic Ordered State on Yb-Based Zigzag Chain Compound YbAgSe2

• Published in: Journal of the Physical Society of Japan Vol. 93; no. 11; p. 1
• Main Authors: Hori, Fumiya, Kitagawa, Shunsaku, Ishida, Kenji, Mizutani, Souichiro, Ohmagari, Yudai, Onimaru, Takahiro
• Format: Journal Article
• Language: English
• Published: Tokyo The Physical Society of Japan 15-11-2024
• Subjects: Anisotropy; Excitation; Low temperature; Magnetic fields; Magnetic induction; Magnetic permeability; Neel temperature; NMR; Nuclear magnetic resonance; Nuclear spin; Spin-lattice relaxation
• ISSN: 0031-9015; 1347-4073
• DOI: 10.7566/JPSJ.93.114702

We report the 77Se-nuclear magnetic resonance (NMR) results of trivalent Yb zigzag chain compound YbAgSe2, which is a sister compound of YbCuS2. The 77Se-NMR spectrum was reproduced by considering two different Se sites with negative Knight shifts and three-axis anisotropy. Above the Néel temperature TN, the Knight shift is proportional to the bulk magnetic susceptibility. Below TN, the extremely broad signal with weak intensity and the relatively sharp signal coexist, suggesting that one is strongly influenced by internal magnetic fields and the other remains relatively unaffected by these fields in the magnetic ordered state. The nuclear spin–lattice relaxation rate 1/T1 remains almost constant above TN and abruptly decreases below TN. In contrast to YbCuS2, a T-linear behavior of 1/T1 at low temperatures was not observed at least down to 1.0 K in YbAgSe2. Our results indicate that the gapless excitation is unique to YbCuS2, or is immediately suppressed in the magnetic fields.