Magnons and continua in a magnetized and dimerized spin-1/2 chain

Article

关键词: SINGLET-GROUND-STATE;    BOSE-EINSTEIN CONDENSATION;    INELASTIC NEUTRON-SCATTERING;    FIELD PHASE-TRANSITION;    LINEAR-CHAIN;    COMPOUND (VO)(2)P2O7;    HEISENBERG CHAIN;    LOW-TEMPERATURE;    SYSTEM;    EXCITATIONS;   

DOI  :  10.1103/PhysRevB.90.094419

来源: SCIE

【 摘 要 】

We examine the magnetic field dependent excitations of the dimerized spin-1/2 chain, copper nitrate, with antiferromagnetic intradimer exchange J(1) = 0.44(1) meV and exchange alternation alpha = J(2)/J(1) = 0.26(2). Magnetic excitations in three distinct regimes of magnetization are probed through inelastic neutron scattering at low temperatures. At low and high fields there are three and two long-lived magnonlike modes, respectively. The number of modes and the antiphase relationship between the wave-vector dependent energy and intensity of magnon scattering reflect the distinct ground states: A singlet ground state at low fields mu H-0 < mu H-0(c1) = 2.8 T and an S-z = 1/ 2 product state at high fields mu H-0 > mu H-0(c2) = 4.2 T. In the intermediate-field regime, a continuum of scattering for (h) over bar omega approximate to J(1) is indicative of a strongly correlated gapless quantum state without coherent magnons.

【 授权许可】

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