1998 Fiscal Year Final Research Report Summary
Spacio-temporal Correlatins and Ground States in Strongly Frustrated Systems
| Project/Area Number |
09640427
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Fukui University |
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Principal Investigator |
MEKATA Mamoru Fac.Engineering, Fukui Univ.Prof., 工学部, 教授 (80025345)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAGI Takeo Fac.Engineering, Fukui Univ.Assis.Prof., 工学部, 助教授 (00206723)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Frustration / Ground state / Triangular Lattice / Kagome Lattice / Tetrahedron Lattice / Singlet State / Quantum Effect |
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| Research Abstract |
The present study was performed to reveal the spacio-temporal correlations and quantum effect in strongly competing systems due to geometrical frustration by means of magnetic measurements on model compounds and computer simulation. The studied model compounds include CsNi(Fe)Cl_3 and BaVS_3 with the triangular lattice of magnetic chains, delafossite type compounds CuFe_<0.95>Al_<0.05>O_2 and A gNiO_2 with the rhombohedrally stacked triangular lattice, SrCr_8Ga_4O_<19> with the Kagome lattice, Cu_9X_2(cpa)_6 nH_2O (X=F,Cl, Br) with the triangulated Kagome lattice, beta-Mn with the corner sharing triangle lattice in three dimension and Y(Sc)Mn_2 with the corner sharing tetrahedron lattice.
The observed ground states of these model compounds may be divided in several groups. CsNi(Fe)C1_3 and CuFe_<0.95> Al_<0.05>O_2 exhibit long range orders due to magnetic interaction between further neighbor spins than the nearest but have complicated magnetic structures due to spin frustration. Frustration gives rize to an orbital ordering in BayS3 with orbital degeneracy. The others have ground states with frozen spins which are different from conventional spin glasses in negative Weiss temperature of large magnitude. Each spinfrozen state exhibits individual features. The reciprocal magnetic susceptibility of SrCr_8Ga_4O_<19> and Cu_6X2(cpa)_3 nH_2O change the temperature gradient at much higher temperature than the spin freezing indicating singlet formation due to quantum effect. The spin freezing found in beta-Mn and Y(Sc)Mn_2 was attributed to the spin freezing of moments induced by lattice defects and it was concluded that the majority spins in these compounds are in spin liquid state. The conditions which determine the classical spin freezing and the quantum freezing are still future problem.
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