Antiferromagnetic ordering driven by the molecular orbital order of C60 in αâ€-Tetra-Kis-(Dimethylamino)-Ethylene-C60

Takashi Kambe, Koichi Kajiyoshi, Motoyasu Fujiwara, Kokichi Oshima

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We have studied the ground state of a fullerene-based magnet, the αâ€-phase tetra-kis-(dimethylamino)-ethylene-C60 (αâ€-TDAE-C60), by electron spin resonance and magnetic torque measurements. Below TN=7  K, nonparamagnetic field dependent resonances with a finite excitation gap (1.7 GHz) are observed along the a axis. Strong enhancement in their intensity as temperature is decreased is inconsistent with excitation from a singlet state, which had been proposed for the αâ€- phase ground state. Below TN, nonquadratic field dependence of the magnetic torque signal is also observed in contrast to quadratic field dependence in the paramagnetic phase. The angle-dependent torque signals below TN indicate the existence of an anisotropy of the bulk magnetization. From both experiments, we propose an antiferromagnetic ground state driven by the cooperative orientational ordering of C60 in the αâ€-TDAE-C60.

Original languageEnglish
Article number177205
JournalPhysical Review Letters
Volume99
Issue number17
DOIs
Publication statusPublished - Oct 23 2007

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torque
molecular orbitals
ethylene
ground state
excitation
fullerenes
electron paramagnetic resonance
magnets
magnetization
anisotropy
augmentation
temperature

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Antiferromagnetic ordering driven by the molecular orbital order of C60 in αâ€-Tetra-Kis-(Dimethylamino)-Ethylene-C60. / Kambe, Takashi; Kajiyoshi, Koichi; Fujiwara, Motoyasu; Oshima, Kokichi.

In: Physical Review Letters, Vol. 99, No. 17, 177205, 23.10.2007.

Research output: Contribution to journalArticle

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title = "Antiferromagnetic ordering driven by the molecular orbital order of C60 in {\^I}±{\^a}€-Tetra-Kis-(Dimethylamino)-Ethylene-C60",
abstract = "We have studied the ground state of a fullerene-based magnet, the {\^I}±{\^a}€-phase tetra-kis-(dimethylamino)-ethylene-C60 ({\^I}±{\^a}€-TDAE-C60), by electron spin resonance and magnetic torque measurements. Below TN=7{\^a}€‰{\^a}€‰K, nonparamagnetic field dependent resonances with a finite excitation gap (1.7{\^A} GHz) are observed along the a axis. Strong enhancement in their intensity as temperature is decreased is inconsistent with excitation from a singlet state, which had been proposed for the {\^I}±{\^a}€- phase ground state. Below TN, nonquadratic field dependence of the magnetic torque signal is also observed in contrast to quadratic field dependence in the paramagnetic phase. The angle-dependent torque signals below TN indicate the existence of an anisotropy of the bulk magnetization. From both experiments, we propose an antiferromagnetic ground state driven by the cooperative orientational ordering of C60 in the {\^I}±{\^a}€-TDAE-C60.",
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AB - We have studied the ground state of a fullerene-based magnet, the αâ€-phase tetra-kis-(dimethylamino)-ethylene-C60 (αâ€-TDAE-C60), by electron spin resonance and magnetic torque measurements. Below TN=7  K, nonparamagnetic field dependent resonances with a finite excitation gap (1.7 GHz) are observed along the a axis. Strong enhancement in their intensity as temperature is decreased is inconsistent with excitation from a singlet state, which had been proposed for the αâ€- phase ground state. Below TN, nonquadratic field dependence of the magnetic torque signal is also observed in contrast to quadratic field dependence in the paramagnetic phase. The angle-dependent torque signals below TN indicate the existence of an anisotropy of the bulk magnetization. From both experiments, we propose an antiferromagnetic ground state driven by the cooperative orientational ordering of C60 in the αâ€-TDAE-C60.

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