Carrier-controlled ferromagnetism in transparent oxide semiconductors.
The search for an ideal magnetic semiconductor with tunable ferromagnetic behaviour over a wide range of doping or by electrical gating is being actively pursued as a major step towards realizing spin electronics. A magnetic semiconductor having a high Curie temperature, capable of independently controlled carrier density and magnetic doping, is crucial for developing spin-based multifunctional devices. Cr-doped In(2)O(3) is such a unique system, where the electrical and magnetic behaviour-from ferromagnetic metal-like to ferromagnetic semiconducting to paramagnetic insulator-can be controllably tuned by the defect concentration. An explicit dependence of magnetic interaction leading to ferromagnetism on the carrier density is shown. A carrier-density-dependent high Curie temperature of 850-930 K has been measured, in addition to the observation of clear magnetic domain structures in these films. Being optically transparent with the above optimal properties, Cr-doped In(2)O(3) emerges as a viable candidate for the development of spin electronics.
Philip
J
J
Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. jphilip@mit.edu
Punnoose
A
A
Kim
B I
BI
Reddy
K M
KM
Layne
S
S
Holmes
J O
JO
Satpati
B
B
Leclair
P R
PR
Santos
T S
TS
Moodera
J S
JS
D000497:Alloys; D002857:Chromium / Q000737:chemistry; D017608:Chromium Compounds / Q000737:chemistry; D003460:Crystallization; D004583:Electrons; D007204:Indium / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008280:Magnetics; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010313:Partial Pressure; D011312:Pressure; D012666:Semiconductors; D013379:Substrate Specificity; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014961:X-Ray Diffraction
D000497:Alloys; D017608:Chromium Compounds; D010087:Oxides; D007204:Indium; D002857:Chromium; D007501:Iron; D010100:Oxygen; C023600:chromic oxide