Carrier-induced Magnetic Circular Dichloism in the Magnetoresistive Pyrochlore Tl_2Mn_2O_7(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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Infrared magnetic circular dichloism (MCD), or equivalently magneto-optical Kerr effect, has been measured on the Tl_2Mn_2O_7 pyrochlore, which is well known for exhibiting a large magnetoresistance around the Curie temperature T_c∿120K. A circularly polarized, infrared synchrotron radiation is used as the light source. A pronounced MCD signal is observed exactly at the plasma edge of the reflectivity near and below T_c. However, contrary to the conventional behavior of MCD for ferromagnets, the observed MCD of Tl_2Mn_2O_7 grows with the applied magnetic field, and not scaled with the internal magnetization. It is shown that these results can be basically understood in terms of a classical magnetoplasma resonance. The absence of a magnetization-scaled MCD indicates a weak spin-orbit coupling of the carriers in Tl_2Mn_2O_7. We discuss the present results in terms of the microscopic electronic structures of Tl_2Mn_2O_7.
一般社団法人日本物理学会の論文
2005-03-15