TY - JOUR
T1 - Ferromagnetic dislocations in antiferromagnetic NiO
AU - Sugiyama, Issei
AU - Shibata, Naoya
AU - Wang, Zhongchang
AU - Kobayashi, Shunsuke
AU - Yamamoto, Takahisa
AU - Ikuhara, Yuichi
N1 - Funding Information:
This study was supported in part by the Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (JSPS) and the Ministry of Education, Culture, Sports and Technology (MEXT). I.S. and S.K. were supported as JSPS research fellows. N.S. acknowledges support from JST-PRESTO and JSPS KAKENHI Grant number 23686093. This work was conducted in the research Hub for Advanced Nano Characterization, the University of Tokyo, supported by MEXT. Part of this work was performed using the facilities of the Cryogenic Research Center at the University of Tokyo. Calculations were conducted on supercomputers at the ISSP, the University of Tokyo.
PY - 2013/4
Y1 - 2013/4
N2 - Crystal lattice defects often degrade device functionality, but engineering these defects may have value in future electronic and magnetic device applications. For example, dislocations - one-dimensional lattice defects with locally distinct atomic-scale structures - exhibit unique and localized electrical properties and can be used as a template for producing conducting nanowires in insulating crystals. It has also been predicted that spin-polarized current may flow along dislocations in topological insulators. Although it is expected that the magnetic properties of dislocations will differ from those of the lattice, their fundamental characterization at the individual level has received little attention. Here, we demonstrate that dislocations in NiO crystals show unique magnetic properties. Magnetic force microscopy imaging clearly reveals ferromagnetic ordering of individual dislocations in antiferromagnetic NiO, originating from the local non-stoichiometry of the dislocation cores. The ferromagnetic dislocations have high coercivity due to their strong interaction with the surrounding antiferromagnetic bulk phase. Although it has already been reported that nanocrystals of rock-salt NiO show ferromagnetic behaviour, our study characterizes the ferromagnetic properties of individual lattice defects. We discuss the origin of the unexpected ferromagnetism in terms of the physical properties of the atomic-scale core structures of single dislocations, and demonstrate that it is possible to fabricate stable nanoscale magnetic elements inside crystalline environments composed of these microstructures.
AB - Crystal lattice defects often degrade device functionality, but engineering these defects may have value in future electronic and magnetic device applications. For example, dislocations - one-dimensional lattice defects with locally distinct atomic-scale structures - exhibit unique and localized electrical properties and can be used as a template for producing conducting nanowires in insulating crystals. It has also been predicted that spin-polarized current may flow along dislocations in topological insulators. Although it is expected that the magnetic properties of dislocations will differ from those of the lattice, their fundamental characterization at the individual level has received little attention. Here, we demonstrate that dislocations in NiO crystals show unique magnetic properties. Magnetic force microscopy imaging clearly reveals ferromagnetic ordering of individual dislocations in antiferromagnetic NiO, originating from the local non-stoichiometry of the dislocation cores. The ferromagnetic dislocations have high coercivity due to their strong interaction with the surrounding antiferromagnetic bulk phase. Although it has already been reported that nanocrystals of rock-salt NiO show ferromagnetic behaviour, our study characterizes the ferromagnetic properties of individual lattice defects. We discuss the origin of the unexpected ferromagnetism in terms of the physical properties of the atomic-scale core structures of single dislocations, and demonstrate that it is possible to fabricate stable nanoscale magnetic elements inside crystalline environments composed of these microstructures.
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U2 - 10.1038/nnano.2013.45
DO - 10.1038/nnano.2013.45
M3 - Article
C2 - 23524441
AN - SCOPUS:84876420065
VL - 8
SP - 266
EP - 270
JO - Nature Nanotechnology
JF - Nature Nanotechnology
SN - 1748-3387
IS - 4
ER -