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Static magnetic order in metallic K0.49CoO2.
J Sugiyama1, H Nozaki, Y Ikedo
1Toyota Central Research and Development Labs, Inc., Nagakute, Aichi 480-1192, Japan. e0589@mosk.tytlabs.co.jp
Physical Review Letters
|February 21, 2006
Summary
Metallic K0.49CoO2 crystals exhibit complex magnetic transitions below 60 K, forming distinct spin density wave (SDW) states. These transitions are primarily influenced by cobalt valence, not interlayer spacing.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid-State Chemistry
Background:
- Potassium cobaltate (K0.49CoO2) is a metallic layered cobaltate.
- Understanding magnetic transitions in correlated electron systems is crucial.
Purpose of the Study:
- To investigate the magnetic properties and phase transitions of K0.49CoO2.
- To elucidate the nature of magnetic ordering in metallic cobaltates.
Main Methods:
- Muon-spin spectroscopy (µSR) was employed to probe magnetic ordering.
- Temperature-dependent measurements were conducted from 4 K to 150 K.
Main Results:
- Successive magnetic transitions were observed at 60 K and 16 K in metallic K0.49CoO2.
- Evidence suggests a commensurate helical spin density wave (SDW) state below 16 K and a linear SDW state above 16 K.
- A transition at 150 K is attributed to a change in cobalt ion spin state.
Conclusions:
- Magnetic order in K0.49CoO2 is strongly dependent on cobalt valence.
- Charge ordering and interlayer interactions play a lesser role in the observed magnetic behavior compared to cobalt valence.