Article Title

Uniform wurtzite MnSe nanocrystals with surface-dependent magnetic behavior

Authors

Jie Zhang, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Fan Zhang, Department of Chemistry, Fudan University, Shanghai 200433, China
Xuebing Zhao, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Xinran Wang, National Laboratory of Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
Lifeng Yin, Department of Physics, Fudan University, Shanghai 200433, China
Chongyun Liang, Department of Chemistry, Fudan University, Shanghai 200433, China
Min Wang, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Ying Li, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Jiwei Liu, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Qingsong Wu, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China
Renchao Che, Department of Materials Science and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China

Keywords

chalcogens, magnetic properties, nanocrystals, transmission electron microscopy

Abstract

ABSTRACT Manganese selenide (MnSe) possesses unique magnetic properties as an important magnetic semiconductor, but the synthesis and properties of MnSe nanocrystals are less developed compared to other semiconductor nanocrystals because of the inability to obtain high-quality MnSe, especially in the metastable wurtzite structure. Here, we have successfully fabricated wurtzite MnSe nanocrystals via a colloidal approach which affords uniform crystal sizes and tailored shapes. The selective binding strength of the amine surfactant is the determining factor in shape-control and shape-evolution. Bullet-shapes could be transformed into shuttle-shapes if part of the oleylamine in the reaction solution was replaced by trioctylamine, and tetrapod-shaped nanocrystals could be formed in trioctylamine systems. The three-dimensional (3D) structure of the bullet-shaped nanorods has been demonstrated by the advanced transmission electron microscope (TEM) 3D-tomography technology. High-resolution TEM (HRTEM) and electron energy-loss spectroscopy (EELS) show that planar-defect structures such as stacking faults and twinning along the [001] direction arise during the growth of bullet-shapes. On the basis of careful HRTEM observations, we propose a “quadra-twin core” growth mechanism for the formation of wurtzite MnSe nanotetrapods. Furthermore, the wurtzite MnSe nanocrystals show low- temperature surface spin-glass behavior due to their noncompensated surface spins and the blocking temperatures increase from 8.4 K to 18.5 K with increasing surface area/volume ratio of the nanocrystals. Our results provide a systematic study of wurtzite MnSe nanocrystals.

Graphical Abstract

DOI

https://doi.org/10.1007/s12274-013-0305-y

Publisher

Tsinghua University Press

Recommended Citation

Jie Zhang,Fan Zhang,Xuebing Zhao,Xinran Wang,Lifeng Yin,Chongyun Liang,Min Wang,Ying Li,Jiwei Liu,Qingsong Wu,Renchao Che, Uniform wurtzite MnSe nanocrystals with surface-dependent magnetic behavior. NanoRes.2013, 6(4): 275–285