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Magnetic resonance in the antiferromagnetic and normal state of NH_3K_3C_60

Ferenc Simon·Andras Janossy·Ferenc Muranyi·Titusz Feher·Hideo Shimoda·Yoshihiro Iwasa·Laszlo Forro
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Abstract

We report on the magnetic resonance of NH_3K_3C_60 powders in the frequency range of 9 to 225 GHz. The observation of an antiferromagnetic resonance below the phase transition at 40 K is evidence for an antiferromagnetically ordered ground state. In the normal state, above 40 K, the temperature dependence of the spin-susceptibilty measured by ESR agrees with previous static measurements and is too weak to be explained by interacting localized spins in an insulator. The magnetic resonance line width has an unusual magnetic-field dependence which is large and temperature independent in the magnetically ordered state and decreases rapidly above the transition. These observations agree with the suggestion that NH_3K_3C_60 is a metal in the normal state and undergoes a Mott-Hubbard metal to insulator transition at 40 K.

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Ferenc Simon, Andras Janossy, Ferenc Muranyi, Titusz Feher, Hideo Shimoda, Yoshihiro Iwasa, Laszlo Forro. 1999-10-20. Magnetic resonance in the antiferromagnetic and normal state of NH_3K_3C_60. https://doi.org/10.1103/physrevb.61.r3826

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