Characterization of material parameters of La_0.33Pr_0.34Ca_0.33MnO₃ thin film by terahertz time-domain spectroscopy

Abstract

We present a systemic study of the terahertz (THz) optical conductivity of a strongly correlated La0.33Pr0.34Ca0.33MnO3 (LPCMO) thin film on a LaAlO3 substrate. The measurements are carried out by THz time-domain spectroscopy in the temperature regime from 15 to 105 K. The frequency-dependent optical conductivity in the metallic phase region of the samples exhibits a non-Drude-like response. We find that below 105 K, both the real and imaginary parts of the complex conductivity can be reproduced by the Drude–Smith model. The important sample and material parameters of the LPCMO thin film (such as the persistence of velocity, the ratio of carrier density to effective mass, and electronic scattering time) can be determined by fitting experimental data. The results obtained agree with those obtained from four-probe electrical transport measurements.

A comparative study on phase co-existence of $$\hbox {La}_{1/4}\hbox {Pr}_{3/8}\hbox {Ca}_{3/8}\hbox {MnO}_{3}$$ in a polycrystalline bulk and thin film

“…In the case of the LPCMO film on LAO, it is observed that the morphology is homogeneous but grainy. This is a typical feature of the LPCMO film grown on the LAO substrate and is well reported in the literature [16,17]. Such an island growth mechanism is attributed to the deposition of a homogeneous wetting layer on the substrate which is topped by the growth of grains at evenly distributed nucleation sites.…”

Microscopic origin of the Drude-Smith model

“…(47). The functional form of the new parameter c(R) is unknown, but since all the parameters of the Monte Carlo simulation are known, we can fit the R dependence of the simulation using only c(R).…”

“…76,77 Fitting these simulations enabled Nemȇc et al to provide approximate mathematical expressions for the Drude-Smith fit parameters 76 that have since been applied to experimental data to extract meaningful physical information. 15,26,27,33,38 Complementary experimental techniques are often also used to examine the structure 11,12,15,[17][18][19][20]22,23,25,26,29,31,[33][34][35][36][37][38][39][41][42][43][44]46,47,50 and carrier transport characteristics 11,12,19,23,26,43,57 in a sample to test the fidelity of the Drude-Smith fits. Nevertheless, in the absence of a tractable derivation that shows how weak carrier confinement yields the Drude-Smith formula with well-understood fit parameters, it is difficult for the Drude-Smith model to be more than a convenient expression for linking the conductivities of similar nanosystems to one another, and to Monte Carlo simulations.…”

Optoelectronic Properties of Monolayer Hexagonal Boron Nitride on Different Substrates Measured by Terahertz Time-Domain Spectroscopy

“…The major advantage of the THz TDS measurement is that the real and imaginary parts of the optical conductivity can be measured directly without involving the Kramers-Kronig (K-K) transformation, and the electron density can be determined in the absence of a magnetic field. Very recently, we measured the key sample and material parameters such as electronic relaxation time, carrier density and electronic localization factor in ML MoS 2 placed on different commonly used substrates [23] and in La 0.33 Pr 0.34 Ca 0.33 MnO 3 thin films [24] by using THz TDS measurements. Using this technique, we have also examined the Faraday rotation effect and obtained the effective electron masses in biand tri-layer graphene in the presence of a magnetic field [25].…”