Abstract
The origin of magnetism in wide-gap semiconductors doped with non-ferromagnetic 3d transition metals still remains intriguing. In this article, insights in the magnetic properties of ordered mesoporous Cu-doped SnO2 powders, prepared by hard-templating, have been unraveled. Whereas, both oxygen vacancies and Fe-based impurity phases could be a plausible explanation for the observed room temperature ferromagnetism, the low temperature magnetism is mainly and unambiguously arising from the nanoscale nature of the formed antiferromagnetic CuO, which results in a net magnetization that is reminiscent of ferromagnetic behavior. This is ascribed to uncompensated spins and shape-mediated spin canting effects. The reduced blocking temperature, which resides between 30 and 5 K, and traces of vertical shifts in the hysteresis loops confirm size effects in CuO. The mesoporous nature of the system with a large surface-to-volume ratio likely promotes the occurrence of uncompensated spins, spin canting, and spin frustration, offering new prospects in the use of magnetic semiconductors for energy-efficient spintronics.
Highlights
Diluted magnetic semiconductors (DMSs) have attracted an extraordinary technological and scientific interest since they may simultaneously exhibit ferromagnetism and semiconducting electric properties, being ideal candidates for novel applications in the field of spintronics [1,2,3]
Insights in the magnetic properties of ordered mesoporous Cu-doped SnO2 powders, prepared by hard-templating, have been unraveled. Both oxygen vacancies and Fe-based impurity phases could be a plausible explanation for the observed room temperature ferromagnetism, the low temperature magnetism is mainly and unambiguously arising from the nanoscale nature of the formed antiferromagnetic CuO, which results in a net magnetization that is reminiscent of ferromagnetic behavior
We report on the preparation of mesoporous Cu-doped SnO2 DMS powders by nanocasting and we investigate the origin of the observed magnetic behavior at room and low temperatures, with the use of magnetometry, and the element selective method of X-ray magnetic circular dichroism (XMCD)
Summary
Diluted magnetic semiconductors (DMSs) have attracted an extraordinary technological and scientific interest since they may simultaneously exhibit ferromagnetism and semiconducting electric properties, being ideal candidates for novel applications in the field of spintronics [1,2,3]. Mesoporous SnO2 has been widely investigated for its potential application in many different fields [33,34,35,36,37,38], magnetism and spintronics studies for this material are overlooked. We report on the preparation of mesoporous Cu-doped SnO2 DMS powders by nanocasting and we investigate the origin of the observed magnetic behavior at room and low temperatures, with the use of magnetometry, and the element selective method of X-ray magnetic circular dichroism (XMCD)
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