基底一重項S=1/2一次元ハイゼンベルグ交替鎖系 (CH_3)_2CHNH_3CuX_3(X=Cl and Br) のNMR=

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The model compound of alternating S=l/2 Heisenberg linear-chain (CH3)2CHNH3CuX3 is synthesized and studied by NMR spin-echo method to investigate the ground-state at low temperatures. The singlet ground-state is confirmed from H nuclear relaxation rate for two isomorphous antiferromagnetic compounds of S=l/2 afternating Heisenberg linear-chain, (CH3)2CHNH3CuCl3 and (CH3)2CHNH3CuBr3. The gap energy 17. 8±0.2 K derived for ferromagnetic-antiferromagnetic alternating chain (CH3)2CHNH3CuCl3 is consistent with that from the susceptibility measurements, while the gap energy 82.0±2.0 K obtained for antiferromagnetic alternating chain (CH3)2CHNH3CuBr3 is discussed taking into account 3-magnon process. Nuclear resonance signals of 63Cu and 65Cu in (CH3)2CHNH3CuCl3 have been detected between 1.5 K and 4.2 K, in view of non magnetic nature of the singlet ground-state.
奈良教育大学の論文