Magnetotransport and magnetism in granular EuS-Co and EuS-Ag nanocomposites prepared by mechanical alloying

Author

Connor, Christine E O ; Feng, Li ; Seip, Candace T. ; Tang, Jinke

Author_Institution

Dept. of Phys., New Orleans Univ., LA, USA

Volume

34

Issue

4

fYear

1998

fDate

7/1/1998 12:00:00 AM

Firstpage

1123

Lastpage

1125

Abstract

Magnetic and magnetotransport properties have been studied in nanocomposites (EuS)-Co and (EuS)-Ag prepared by mechanical alloying. For (EuS)₇₀Co₃₀, the large negative magnetoresistance (~50%) found at 20 K, just above the Curie temperature (T_c) of EuS, arises from the suppression of spin fluctuation in EuS. Below T_c, the positive magnetoresistance (~15%), which is uncharacteristic of ferromagnetic semiconductors, is probably due to defect-induced magnetic fluctuation. On the other hand, (EuS)₇₀Ag₃₀, where nonmagnetic silver replaces cobalt, exhibits negative magnetoresistance below T_c, which is possibly related to the spin dependent scattering commonly seen in GMR materials. While (EuS)₇₀Co₃₀ shows semiconducting conductivity, (EuS)₇₀Ag₃₀ is metallic. Reentrant spin glass behavior has been observed in EuS-Ag system, where the rise of antiferromagnetic coupling is due to the defects and disorder caused by mechanical milling

Keywords

Curie temperature; cobalt; composite materials; europium compounds; ferromagnetic materials; granular materials; magnetic particles; magnetic semiconductors; magnetoresistance; mechanical alloying; nanostructured materials; silver; spin fluctuations; spin glasses; (EuS)₇₀Ag₃₀; (EuS)₇₀Co₃₀; 20 K; Curie temperature; EuS-Ag; EuS-Ag nanocomposites; EuS-Co; antiferromagnetic coupling; defect-induced magnetic fluctuation; defects; disorder; ferromagnetic semiconductors; granular EuS-Co nanocomposites; large negative magnetoresistance; magnetism; magnetotransport; mechanical alloying; mechanical milling; metallic conductivity; negative magnetoresistance; positive magnetoresistance; reentrant spin glass behavior; semiconducting conductivity; spin dependent scattering; spin fluctuation; Alloying; Antiferromagnetic materials; Fluctuations; Giant magnetoresistance; Magnetic materials; Magnetic properties; Magnetic semiconductors; Mechanical factors; Nanocomposites; Temperature;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.706402

Filename

706402