Budget Amount *help 
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1995 : ¥1,600,000 (Direct Cost : ¥1,600,000)

Research Abstract 
The quantum spin effect is one of the most interesting subjects in the physics of magnetism at low temperatures. Of these, the quantum spingap attracts much attention. Various origins of the spingap are known and they are classified into two categories. The one is due to the single or twospin origin, such as single ion anisotropy, antiferromagnetic (AF) coupled spin pair, etc. The other is due to many body quantum spin origin in onedimensional AF linear chain, such as the Haldane effect, the spinPeierls transition etc. Above all, the quantum spingap due to the many body spin effect in onedimensional antiferromagnet has become an exciting problem, when Haldane has predicted the existence of the spingap in onedimensional Heisenberg antiferromagnet with integer spin. Until that time, it was believed that the spingap did not exist in such a system. The exact theoretical solution of S=1/2 Heisenberg AF chain shows no spingap between the ground state and the first excited state. Si
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nce it was considered that the quantum spin effect should be expected most clearly in S=1/2 system, Haldane's prediction was sensational. Since then, many theoretical and experimental works have been performed to reveal that the Haldane conjecture is true. It should be noted that the S=1/2 uniform Heisenberg AF chain has no spingap, while that the chain with bond alternation has a spingap. On the quantum spingap in the S=1/2 Heisenberg AF chain with bond alternation, the first observation of the spinPeierls transition has recently been reported in an inorganic material CuGeO_3. The SPphase, which has a spingap, is a onedimensional AF chain with bond alternation. In order to clarify the spingap in SPphase we have made an NMR experiment on CuCl_2 (gammapicoline) _2, which has crystallographic bond alternation. These spingaps have been studied through NMR experiments. The spin echo spectrum and the nuclear spinlattice relaxation under high magnetic fields have been performed and compared. Less
