| Project/Area Number |
13440106
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅱ(磁性・金属・低温)
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
SAKAKIBARA Toshiro The University of Tokyo, Institute For Solid State Physics, Professor, 物性研究所, 教授 (70162287)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TAYAMA Takashi The University of Tokyo, Institute For Solid State Physics, Research Associate, 物性研究所, 助手 (20334344)
|
|---|
| Project Period (FY) |
2001 – 2003
|
| Project Status |
Completed (Fiscal Year 2003)
|
| Budget Amount *help |
¥14,800,000 (Direct Cost: ¥14,800,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 2001: ¥9,100,000 (Direct Cost: ¥9,100,000)
|
|---|
| Keywords | quadrupole ordering / anisotropic quadrupole interaction / anisotropic superconductivity / gap symmetry / spin ice / skutterudite / magnetization measurement / specific heat measurement / 角度分解磁化測定 / 角度分解比熱測定 / 磁気熱量効果 / 反強四重極相図 / d波超伝導ギャップ構造 / スピンアイス化合物 / 気相液相型相転移 / エントロピー変化 / 気相液相転移 / 磁場誘起秩序状態 / 上部臨界磁場 / 不純物効果 / 非フェルミ液体的振舞い / 結晶場基底状態 / 残留状態密度 / 連続角度変化 / 常磁性効果 / メタ磁性転移 |
|---|
| Research Abstract |
1.We developed a new magnetometer that can rotate the field direction continuously at low temperatures below 0.5 K. Using this magnetometer, we examined the phase diagram of an antiferro-quadrupole ordering system PrPb3 and obtained the field-angle variation of the transition temperature. From the results, we could identify the order parameter, which requires the quadrupole interaction to be anisotropic.
2.We developed a new calorimeter that can rotate magnetic field direction continuously at low temperatures below 0.5 K. Using this calorimeter, we investigated the low temperature specific heat of the anisotropic superconductor CeCoIn5 in the superconducting mixed state. We observed a clear fourfold angular oscillation of the electronic specific heat, indicating d wave superconductivity. From the angular position of the minima in the specific heat, the d_xy type gap symmetry is concluded.
3.Magnetization process of a spin-ice compound Dy2Ti2O7 has been examined in a (111] magnetic field. We observed a clear magnetization plateau in the kagome ice state, followed by a first-order transition to a saturated sate. The transition is found to be of a liquid-gs type, which is new for the localized spin systems.
4.Field-temperature phase diagrams of the skutterudite compound PrOs4Sb12 has been examined at low temperatures and a field-induced ordering is observed for all the principal field directions. The results indicate the ground state of this system to be a Gamma_1 singlet.
|
