Critical thickness for ferromagnetism in LaAlO3/SrTiO3 heterostructures

被引：187
作者：
Kalisky, Beena [1 ,2 ]
Bert, Julie A. [1 ]
Klopfer, Brannon B. [2 ]
Bell, Christopher [1 ]
Sato, Hiroki K. [1 ,3 ]
Hosoda, Masayuki [1 ,3 ]
Hikita, Yasuyuki [1 ]
Hwang, Harold Y. [1 ]
Moler, Kathryn A. [1 ]
机构：
[1] SLAC Natl Accelerator Lab, Stanford Inst Mat & Energy Sci, Menlo Pk, CA 94025 USA
[2] Bar Ilan Univ, Dept Phys, Nanomagnetism Res Ctr, Inst Nanotechnol & Adv Mat, IL-52900 Ramat Gan, Israel
[3] Univ Tokyo, Dept Adv Mat Sci, Kashiwa, Chiba 2778561, Japan
来源：
NATURE COMMUNICATIONS | 2012年 / 3卷
基金：
美国国家科学基金会;
关键词：
ELECTRON-GAS; INTERFACE; SUPERCONDUCTIVITY; COEXISTENCE;
D O I：
10.1038/ncomms1931
中图分类号：
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号：
07 ; 0710 ; 09 ;
摘要：
In LaAlO3/SrTiO3 heterointerfaces, charge carriers migrate from the LaAlO3 to the interface in an electronic reconstruction. Magnetism has been observed in LaAlO3/SrTiO3, but its relationship to the interface conductivity is unknown. Here we show that reconstruction is necessary, but not sufficient, for the formation of magnetism. Using scanning superconducting quantum interference device microscopy we find that magnetism appears only above a critical LaAlO3 thickness, similar to the conductivity. We observe no change in ferromagnetism with gate voltage, and detect ferromagnetism in a non-conducting p-type sample. These observations indicate that the carriers at the interface do not need to be itinerant to generate magnetism. The ferromagnetism appears in isolated patches whose density varies greatly between samples. This inhomogeneity strongly suggests that disorder or local strain generates magnetism in a population of the interface carriers.
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页数：6
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