2005 Fiscal Year Final Research Report Summary
Study of quantum magnetism in nano spin polyhedrons
| Project/Area Number |
16340107
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics II
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
NOJIRI Hiroyuki Tohoku University, Institute for Materials Research, Professor, 金属材料研究所, 教授 (80189399)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUDA Yasuhiro Okayama University, Graduate School of Natural Science, Associate Professor, 大学院・自然科学研究科, 助教授 (10292757)
OSHIMA Yugo Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (10375107)
KWANG-YONG Choi Tohoku University, Institute for Materials Research, Research Associate, 金属材料研究所, 助手 (20375108)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | single molecular magnet / high magnetic field / quantum information / magnetism / spin polyhedron |
|---|
| Research Abstract |
Spin polyhedrons are antiferromagnetic spin clusters of high symmetry without disorders. Variety of magnetic networks is possible because a translational symmetry in not needed in such clusters. We have investigated two types of clusters Mo72Fe30 and Fe9. The former cluster is so called corner-sharing network of triangles and latter is the edge-sharing network. The spin frustration is strong and the energy state is highly degenerated.
The Mo72Fe30 shows a dip of derivative magnetization at the 1/3 of full magnetization and the origin of dip has been interpreted by the "order by disorder" mechanism. At low temperature, the system shows a broad anomaly in specific heat and in ESR line width. This phenomenon is interpreted as "quasi long range order" caused by the saturation of intra-cluster magnetic correlation. As for the size effect, the smearing of magnetization step is confirmed in Mo72Fe30, where the energy separation among the discrete levels is smaller than the mixing term such as staggered fields and anti-symmetric exchange interaction. On the other hand, clear steps are found in Fe9 and the reduction of the step magnetization is attributed to the asymmetric mixing caused by the spin chirality.
The dynamics of the triangle spin ring, which is an important component of spin polyhedrons, has been investigated. A clear adiabatic magnetization and half-step magnetization phenomenon is found. The comparison of magnetization process is made with different systems such as two-nuclear complex and rare earth based cluster. The importance of spin chirality is examined in various system such as spin tube.
|
