NaxCoO2:: Enhanced low-energy excitations of electrons on a 2d triangular lattice

被引：9

作者：

Bruehwiler, M. ^{[1
]}

Batlogg, B.

Kazakov, S. M.

Niedermayer, Ch.

Karpinski, J.

机构：

[1] ETH, Solid State Phys Lab, CH-8093 Zurich, Switzerland

[2] Paul Scherrer Inst, Neutron Scattering Lab, CH-5232 Villigen, Switzerland

来源：

PHYSICA B-CONDENSED MATTER | 2006年 / 378-80卷

关键词：

NaxCoO2; spin fluctuations; thermodynamic properties; triangular lattice; SDW; muon spin rotation;

D O I：

10.1016/j.physb.2006.01.422

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

To elucidate the low-energy excitation spectrum of correlated electrons on a 2D triangular lattice, we have studied the electrical resistance and specific heat down to 0.5 K and in magnetic fields up to 14T, in NaxCoO2 samples with a Na content ranging from x 0.5 to 0.82. Two distinct regimes are observed: for x from about 0.64 to x approximate to 0.75 the specific heat is strongly enhanced, with a pronounced upturn of C,IT below about 10K, reaching 47mJ/(mol K-2). This enhancement is suppressed in a magnetic field indicative of strong low-energy spin fluctuations. At higher Na content, the fluctuations are reduced and mu SR data confirm the SDW ground state below 22 K and the much reduced heat capacity is field independent. (c) 2006 Elsevier B.V. All rights reserved.

引用

页码：630 / 631

页数：2

共 14 条

[1] Charge ordering, commensurability, and metallicity in the phase diagram of the layered NaxCoO2 -: art. no. 247001 [J].

Foo, ML ;

Wang, YY ;

Watauchi, S ;

Zandbergen, HW ;

He, T ;

Cava, RJ ;

Ong, NP .

PHYSICAL REVIEW LETTERS, 2004, 92 (24) :247001-1

[2] Unconventional charge ordering in Na0.70CoO2 below 300 K -: art. no. 100404 [J].

Gavilano, JL ;

Rau, D ;

Pedrini, B ;

Hinderer, J ;

Ott, HR ;

Kazakov, SM ;

Karpinski, J .

PHYSICAL REVIEW B, 2004, 69 (10)

[3] Effective interaction between the interpenetrating Kagome lattices in NaxCoO2 -: art. no. 214414 [J].

Indergand, M ;

Yamashita, Y ;

Kusunose, H ;

Sigrist, M .

PHYSICAL REVIEW B, 2005, 71 (21)

[4] Observation of bulk superconductivity in NaxCoO2•yH2O and NaxCoO2•yD2O powder and single crystals -: art. no. 217001 [J].

Jin, R ;

Sales, BC ;

Khalifah, P ;

Mandrus, D .

PHYSICAL REVIEW LETTERS, 2003, 91 (21)

[5] Unconventional magnetic transition and transport behavior in Na0.75CoO2 -: art. no. 064406 [J].

Motohashi, T ;

Ueda, R ;

Naujalis, E ;

Tojo, T ;

Terasaki, I ;

Atake, T ;

Karppinen, M ;

Yamauchi, H .

PHYSICAL REVIEW B, 2003, 67 (06)

[6] STRONGLY GEOMETRICALLY FRUSTRATED MAGNETS [J].

RAMIREZ, AP .

ANNUAL REVIEW OF MATERIALS SCIENCE, 1994, 24 :453-480

[7] Thermal and electrical properties of γ-NaxCoO2 (0.70≤x≤0.78) [J].

Sakurai, H ;

Tsujii, N ;

Takayama-Muromachi, E .

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 2004, 73 (09) :2393-2396

[8] Electronic structure of NaCo2O4 [J].

Singh, DJ .

PHYSICAL REVIEW B, 2000, 61 (20) :13397-13402

[9] Static magnetic order in Na0.75CoO2 detected by muon spin rotation and relaxation -: art. no. 214420 [J].

Sugiyama, J ;

Itahara, H ;

Brewer, JH ;

Ansaldo, EJ ;

Motohashi, T ;

Karppinen, M ;

Yamauchi, H .

PHYSICAL REVIEW B, 2003, 67 (21)

[10] Superconductivity in two-dimensional CoO2 layers [J].

Takada, K ;

Sakurai, H ;

Takayama-Muromachi, E ;

Izumi, F ;

Dilanian, RA ;

Sasaki, T .

NATURE, 2003, 422 (6927) :53-55

← 1 2 →