Ferromagnetism and Luminescence of Diluted Magnetic Semiconductors GaGdN and AlGdN
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1111-D03-01
Ferromagnetism and Luminescence of Diluted Magnetic Semiconductors GaGdN and AlGdN
Shuichi Emura1, Masahiro Takahashi1, Hiroyuki Tambo1, Akira Suzuki2, T. Nakamura3, Yi.-Kai Zhou1, Shigehiko Hasegawa1, and Hajime Asahi1 1
ISIR, Osaka University Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan
2
Research Organization of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577,
Japan 3
JASRI/SPring-8, Kouto 1-1-1, Sayocho, Sayogun, Hyogo 679-5198, Japan
ABSTRACT The magnetic characteristics of the dilute magnetic system GaGdN are investigated mainly by soft-X-ray magnetic circular dichroism (MCD) in the energy range of 1160 – 1240 eV. The strong MCD signals up to 30 % at 15K are observed. The temperature dependence of the signal intensity is not on a simple Curie-Weiss curve but depicts a three-step curve. A step around 40 – 100K suggests a new magnetic phase. The luminescence spectrum of GaGdN at low temperature is divided into three parts consisting of two broad bands around 432 nm and 503 nm and a sharp peak at 652 nm. This sharp line is assigned to the intra-transition of the f – f orbital owing to the weak temperature dependence of the intensity and the peak position. AlGdN grown by molecular beam epitaxy produces luminescence at 318.5 nm. X-ray absorption fine structure is examined to survey the occupancy of the Gd ion in the grown specimens.
INTRODUCTION The fusion of electronics, photonics and magnetism may lead to produce multi-functional devices. Magneto-electronics is a new developing research field, where two kinds of physical freedom of charge and spin of the carriers will be simultaneously utilized to create new functionalities in the practical device applications. The new devices based on above would have the advantages of no volatility, increased data processing speed, decreased electric power, and increased integration densities compared with commercial based semiconductors. As one of the highly active research fields in the fusion region, magnetic semiconductors are given the revival attention. It is the reason why new materials such as GaMnAs, which very suitably fuses to semiconductor characteristics, have been developed recently.
Our material, GaGdN (AlGdN), picked up in this meeting produces three functional properties, namely ferromagnetism at room temperature and luminescence properties in addition to the essential semiconductor nature. Teraguchi et al. found room temperature operation of the ferromagnetic behavior and simultaneously observed a strange cathode luminescence around the green ~ red color region [1]. After this work, Berlin group has confirmed similar ferromagnetic behavior in a very dilute concentration specimen (7x1015/cm3), resulting in the magnetic moment up to 4000 µB per one Gd ion, surprisingly [2]. They deeply promoted their investigation using various experimental methods [3-5]. The Gd-ion-implanted specimen also showed roomtemperature ferromagnetism, and the annealing of the ion-implanted specimen decreased the ferromagnetic degree. Thu
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