Muon Spin Relaxation Measurements on a Spin–Ladder Material Na₂Co₂(C₂O₄)₃(H₂O)₂

Muon spin relaxation detection of the soft mode toward the exotic magnetic ground state in the bond-disordered quantum spin systemIPA-Cu(Cl0.35Br0.65Goto1, Suzuki2, Kanada3 et al. 2008Phys. Rev. BSelf Cite272140View full textAdd to dashboardCite

“…[27][28][29] As for the other two with x=0.95 and 0.88, which are outside of the two QCPs, and hence were believed to be gapped, we confirmed that though they do not show a magnetic order down to the dilution temperature region [31], their spin relaxation rate stay at anomalously high value [27,30]. Though this fact at first glance suggests that their ground state is magnetic, many µSR reports performed so far on other quantum spin systems warn that it is dangerous to judge the ground state to be magnetic or non magnetic only from the magnitude of the muon spin relaxation rate [32,33,34,35].…”

“…25,29 Although this fact at first glance suggests that their ground state is magnetic, many SR reports performed so far on other quantum spin systems warn that it is dangerous to judge the ground state to be magnetic or nonmagnetic only from the magnitude of the SR rate. [30][31][32][33][34] In order to determine the ground state of quantum spin systems, we have developed a simple way to obtain a spinfluctuation spectrum from SR experiments under longitudinal field ͑LF͒. In this paper, we present an application of this method to a Br-rich sample with x = 0.35, which was reported by macroscopic experiments to be the singlet dimer phase ͑the same as x =0͒ and have a finite spin excitation energy.…”

μSR-detected soft mode toward a possible phase transition in a disordered spin-gap system, (CH3)2CHNH3–Cu(ClxBr1−x)3

“…The static field distribution width ∆ was about 0.2 µs −1 , was temperature independent within an experimental resolution, and was considered to be from the quasi static nuclear spin contribution [18,19,14]. Note that the magnitude of λ 2 is very large, hiding the effect of nuclear contribution, so that G KT is omitted in the second term.…”

“…where G KT is the Kubo-Toyabe function [18,19] with parameters of a static field distribution width at the muon site ∆, relaxation rates λ 1 and λ 2 , and component amplitudes A 1 and A 2 . The static field distribution width ∆ was about 0.2 µs −1 , was temperature independent within an experimental resolution, and was considered to be from the quasi static nuclear spin contribution [18,19,14]. Note that the magnitude of λ 2 is very large, hiding the effect of nuclear contribution, so that G KT is omitted in the second term.…”

“…As is reported on many other quantum spin systems [14,15], one cannot judge their ground state to be gapped or gapless simply from the temperature dependence of the muon spin relaxation rate. In this article, we show that the characteristic frequency of dynamical spin fluctuation decreases toward zero with decreasing temperature, suggesting the existence of a magnetic order at absolute zero or an extremely low temperature.…”