Studies of quenched disorder in La0.7Ca0.3MnO3-type CMR manganite system from magnetic, transport and positron annihilation spectroscopic measurements

2007 ◽  
Vol 398 (1) ◽  
pp. 23-27 ◽  
Author(s):  
S. Chattopadhyay ◽  
A. Sarkar ◽  
Sudipta Pal ◽  
S.D. Kulkarni ◽  
P.A. Joy ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Quenched Disorder ◽  
Spectroscopic Measurements ◽  
Magnetic Transport ◽  
Cmr Manganite

scholarly journals Development of Positron Microbeam in AIST

2008 ◽  
Vol 607 ◽  
pp. 238-242 ◽  
Author(s):  
Nagayasu Oshima ◽  
Ryoichi Suzuki ◽  
Toshiyuki Ohdaira ◽  
Atsushi Kinomura ◽  
T. Narumi ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Spatial Resolution ◽  
Transport System ◽  
Linear Accelerator ◽  
Positron Beam ◽  
Positron Annihilation Spectroscopy ◽  
Beam Size ◽  
Electron Linear Accelerator ◽  
Slow Positron ◽  
Magnetic Transport

To improve the spatial resolution of positron annihilation spectroscopy (PAS), a system to produce an intense positron microbeam was developed in AIST. A slow positron beam, which was produced by an electron linear accelerator, was focused by a lens onto a remoderator to enhance its brightness. The brightness-enhanced beam with an intensity of ≈1 × 106 e+/s was extracted from the remoderator and focused onto the sample by a lens. The beam size at the sample was 25 μm, which is more than two and half orders of magnitude smaller than that in the magnetic transport system (≈10 mm). Hence, the spatial resolution of PAS with an AIST positron microbeam can be drastically improved relative to PAS using conventional methods.

Positron Annihilation in Semiconductors

1999 ◽  
Author(s):  
Reinhard Krause-Rehberg ◽  
Hartmut S. Leipner
Keyword(s):  
Positron Annihilation

Emergence of size induced metallic state in the ferromagnetic insulating Pr0.8Sr0.2MnO3 manganite: Breaking of surface polarons

2015 ◽  
Vol 8 (2) ◽  
pp. 2084-2093 ◽  
Author(s):  
PROLOY TARAN DAS ◽  
Arun Kumar Nigam ◽  
Tapan Kumar Nath
Keyword(s):  
Transport Properties ◽  
Metallic State ◽  
Temperature Dependent ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
System A ◽  
Surface Disorder ◽  
Bulk System ◽  
Magnetic Transport ◽  
Grain Surface

Nano-dimensional effects on electronic-, magneto-transport properties of granular ferromagnetic insulating (FMI) Pr0.8Sr0.2MnO3 (PSMO) manganite (down to 40 nm) have been investigated in details. From the electronic and magnetic transport properties, a metallic state has been observed in grain size modulation by suppressing the ferromagnetic insulating state of PSMO bulk system. A distinct metal-insulator transition (MIT) temperature around 150 K has been observed in all nanometric samples. The observed insulator to metallic transition with size reduction can be explained with surface polaron breaking model, originates due to enhanced grain surface disorder. This proposed phenomenological polaronic model plays a significant role to understand the polaronic destabilization process on the grain surface regime of these phase separated nano-mangnatie systems. Temperature dependent resistivity and magnetoresistance data in presence of external magnetic fields are investigated in details with various compatible models.

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