Electronic properties of GaV4S8: A percolation approach

Pramana

S Hansda²  A K Rastogi¹  I Naik1² 

[1] School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110 067, India$$;Department of Physics, North Orissa University, Baripada 757 003, India$$

关键词: Transition metal compound;    percolation theory;    magnetoresistance.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

Two polycrystalline V4-cluster compounds of GaV4S8 were prepared at different annealing temperatures (GaV4S8-1 sintered at 800°C and GaV4S8-2 sintered at 500°C). Their temperature-dependent resistivity and structural phase transformation temperature (45 K for GaV4S8-1 and 43K for GaV4S8-2) are found to be very sensitive to the annealing condition. Above 320 K, activation energy 𝜀3 is calculated to be ∼0.23 eV which decreases to ∼0.18 eV around 300 K in GaV4S8-1 and GaV4S8-2 on cooling. According to percolation theory, the gradual decrease in 𝜀3 below 300 K is expected due to the increase in separation between V4-clusters are significantly different in GaV4S8-1 and GaV4S8-2. This statement is strongly supported by the calculated bandwidth 𝛤 per cluster in GaV4S8 (∼0.342 eV in GaV4S8-1 and ∼0.374 eV in GaV4S8-2). A negative magnetoresistance (MR) is also found around 43 K in GaV4S8-2 at 6.0 T magnetic field associated with structural transition.

【 授权许可】

Unknown