μSR and NMR study on quantum critical point in quantum spin ladder (CH3)2CHNH3Cu(ClxBr1−x)3

• Published in: Journal of physics. Conference series 2010-01, Vol.200 (2), p.022036
• Main Authors: Nakajima, S, Goto, T, Suzuki, T, Watanabe, I, Manaka, H, Amato, A
• Format: Article
• Language: English
• Subjects: Critical point; Ground state; Low temperature; Muon spin relaxation; NMR; Nuclear magnetic resonance; Physics
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/200/2/022036

(CH3)2CHNH3Cu(ClxBr1-x)3 abbreviated IPACu(ClxBr1-x)3 is a mixed system of spin-gap compounds IPACuCl3 and IPACuBr3. This mixed system is reported by macroscopic measurements to show a magnetic order when the value of x is between the quantum critical points (QCPs) 0.44 and 0.87. We have investigated microscopically the ground state of the samples x 0.40, 0.45 and 0.50 which are located near the QCP of xc 0.44, by Muon Spin Relaxation (μSR) and NMR measurements. For x 0.40, μSR measurements in zero and longitudinal fields have shown that the spin fluctuation shows a significant slowing down with decreasing temperature, although the magnetic order does not appear down to T 15 mK, indicating that the ground state is an exotic one rather than a gapped one. For x 0.45 and 0.50, μSR and NMR measurements do not show any magnetic order at low temperatures, indicating that the QCP is larger than the reported value of xc 0.44.