Bid, Aveek and Raychaudhuri, Arup K (2003) Low frequency noise in charge ordered system $Pr_0_._6_3Ca_0_._3_7MnO_3$ near the charge-ordering transition and in the current induced destabilized state. In: Second International Symposium on luctuations and Noise, 2 June 2003, Santa Fe, USA, pp. 144-155.Full text not available from this repository.
We have investigated the specific issue of dynamics of co-existing phases in the Charge Ordered (CO) manganite system $Pr_0_._6_3Ca_0_._3_7MnO_3$ using the technique of conductance noise spectroscopy. We note that close to the CO transition temperature $T_c_o$ the spectral power of $Sv(f)/V^2$ deviates significantly from the 1/f frequency dependence for f \leq 0.12Hz. Our analysis shows that this deviation can be described by a single frequency Lorentzian with corner frequency $f_c$ in addition to the usual broadband 1/f noise. Such a Lorentzian contribution to $S_v(f)/V^2$ can come from a two level system (TLS). In the time serioues this shows up as RTN. For T \leq $T_c_o$ the system shows the onset of a non-linear conduction close to a threshold value $J_d_c = J_t_h$ the noise spectra is mainly 1/f in nature. $For J > J_t_h$ a large low frequency component of noise (characterized again by a frequency $f_c$) appears. We associate $f_c$ with the relaxation time tc of the TLS fluctuator so the tc = $1/f_c$. For thermal activation of the TLS the temperature dependence of $f_c$ will follow $f_c=f_oexp(-E_a/k_BT)$ where $E_a$ is an energy barrier. The value of $f_c$ shows an increase with $J_d_c$ showing that the value of the activation energy $E_a$ is being lowered by the applied bias.
|Item Type:||Conference Paper|
|Additional Information:||Copyright of this article belongs to SPIE-The International Society for Optical Engineering.|
|Department/Centre:||Division of Physical & Mathematical Sciences > Physics|
|Date Deposited:||15 Dec 2005|
|Last Modified:||25 Jan 2012 10:18|
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