Low-temperature magnetoresistance of layered cobalt oxides Nax CoO2

Hirotaka Okabe; Jun Akimitsu; Takashi Kubodera; Masanori Matoba; Toru Kyomen; Mitsuru Itoh

doi:10.1016/j.physb.2006.01.319

Low-temperature magnetoresistance of layered cobalt oxides Na_x CoO₂

Hirotaka Okabe, Jun Akimitsu, Takashi Kubodera, Masanori Matoba, Toru Kyomen, Mitsuru Itoh

Department of Applied Physics and Physico-Informatics

Research output: Contribution to journal › Article › peer-review

24 Citations (Scopus)

Abstract

We measured transport properties in layered cobalt oxides Na_x CoO₂, that are parent materials of the superconductor Na_x CoO₂ · y H₂ O, in order to reveal so-far unsettled origin of these electronic and magnetic features. Various sodium nonstoichiometric samples Na_x CoO₂ ( x = 0.47, 0.62, 1.0) have been carefully synthesized to control the carrier density and the electronic state of cobalt ions. We found a large negative magnetoresistance (MR) effect in the vicinity of x ∼ 0.5 and 1.0. The x = 0.47 and 1.0 samples show negative MR, - 45 % and - 10 %, respectively, at 90 kOe and 4 K. These negative MR suggest the pseudogap formation due to the charge ordering in CoO₂ layers, such as Ca₃ Co₄ O₉ and Bi_{2 - x} Pb_x Sr₂ Co₂ O_y, all of which exhibit similar behaviors. The suppression of the pseudogap by a magnetic field causes the large negative magnetoresistance.

Original language	English
Pages (from-to)	863-864
Number of pages	2
Journal	Physica B: Condensed Matter
Volume	378-380
Issue number	SPEC. ISS.
DOIs	https://doi.org/10.1016/j.physb.2006.01.319
Publication status	Published - 2006 May 1

Keywords

Cobalt oxide
Magnetoresistance
Transport property

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Electrical and Electronic Engineering

Access to Document

10.1016/j.physb.2006.01.319

Cite this

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title = "Low-temperature magnetoresistance of layered cobalt oxides Nax CoO2",

abstract = "We measured transport properties in layered cobalt oxides Nax CoO2, that are parent materials of the superconductor Nax CoO2 · y H2 O, in order to reveal so-far unsettled origin of these electronic and magnetic features. Various sodium nonstoichiometric samples Nax CoO2 ( x = 0.47, 0.62, 1.0) have been carefully synthesized to control the carrier density and the electronic state of cobalt ions. We found a large negative magnetoresistance (MR) effect in the vicinity of x ∼ 0.5 and 1.0. The x = 0.47 and 1.0 samples show negative MR, - 45 % and - 10 %, respectively, at 90 kOe and 4 K. These negative MR suggest the pseudogap formation due to the charge ordering in CoO2 layers, such as Ca3 Co4 O9 and Bi2 - x Pbx Sr2 Co2 Oy, all of which exhibit similar behaviors. The suppression of the pseudogap by a magnetic field causes the large negative magnetoresistance.",

keywords = "Cobalt oxide, Magnetoresistance, Transport property",

author = "Hirotaka Okabe and Jun Akimitsu and Takashi Kubodera and Masanori Matoba and Toru Kyomen and Mitsuru Itoh",

note = "Funding Information: This work is supported in part by Grant in Aids for Science Research of Priority Area “Invention of anomalous quantum materials” from Ministry of Education, Culture, Sport, and Technology in Japan. This work was partially performed under Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology.",

year = "2006",

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doi = "10.1016/j.physb.2006.01.319",

language = "English",

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T1 - Low-temperature magnetoresistance of layered cobalt oxides Nax CoO2

AU - Okabe, Hirotaka

AU - Akimitsu, Jun

AU - Kubodera, Takashi

AU - Matoba, Masanori

AU - Kyomen, Toru

AU - Itoh, Mitsuru

N1 - Funding Information: This work is supported in part by Grant in Aids for Science Research of Priority Area “Invention of anomalous quantum materials” from Ministry of Education, Culture, Sport, and Technology in Japan. This work was partially performed under Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology.

PY - 2006/5/1

Y1 - 2006/5/1

N2 - We measured transport properties in layered cobalt oxides Nax CoO2, that are parent materials of the superconductor Nax CoO2 · y H2 O, in order to reveal so-far unsettled origin of these electronic and magnetic features. Various sodium nonstoichiometric samples Nax CoO2 ( x = 0.47, 0.62, 1.0) have been carefully synthesized to control the carrier density and the electronic state of cobalt ions. We found a large negative magnetoresistance (MR) effect in the vicinity of x ∼ 0.5 and 1.0. The x = 0.47 and 1.0 samples show negative MR, - 45 % and - 10 %, respectively, at 90 kOe and 4 K. These negative MR suggest the pseudogap formation due to the charge ordering in CoO2 layers, such as Ca3 Co4 O9 and Bi2 - x Pbx Sr2 Co2 Oy, all of which exhibit similar behaviors. The suppression of the pseudogap by a magnetic field causes the large negative magnetoresistance.

AB - We measured transport properties in layered cobalt oxides Nax CoO2, that are parent materials of the superconductor Nax CoO2 · y H2 O, in order to reveal so-far unsettled origin of these electronic and magnetic features. Various sodium nonstoichiometric samples Nax CoO2 ( x = 0.47, 0.62, 1.0) have been carefully synthesized to control the carrier density and the electronic state of cobalt ions. We found a large negative magnetoresistance (MR) effect in the vicinity of x ∼ 0.5 and 1.0. The x = 0.47 and 1.0 samples show negative MR, - 45 % and - 10 %, respectively, at 90 kOe and 4 K. These negative MR suggest the pseudogap formation due to the charge ordering in CoO2 layers, such as Ca3 Co4 O9 and Bi2 - x Pbx Sr2 Co2 Oy, all of which exhibit similar behaviors. The suppression of the pseudogap by a magnetic field causes the large negative magnetoresistance.

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