Transport And Electrothermal Properties Of Epitaxial Strontium Ruthenate Thin Films

SrRuO₃（SRO）is a touring ferromagnetic material with a chalcogenide structure.Due to their high electrical conductivity and chemical stability,SRO films are often used as conductive electrodes in microelectronic devices.SRO films have a strong spin polarization at Curie temperature and can be used in magnetic storage devices.Van der Waals epitaxial growth is a technique that has attracted much attention in recent years with the rise of two-dimensional materials,and the method is gradually being applied to the study of functional oxide films.In this paper,van der Waals epitaxial growth of SRO has been successfully achieved using mica as a substrate.We focus on the orientation control of van der Waals epitaxial films,a direction that has not yet received much attention in this field.The main results of the paper are as follows.（1）Transition layer structures were designed to control the oriented growth of SRO films.The optimum growth parameters for[111]and[110]oriented SRO films were determined through a series of experiments.The[111]oriented SRO films were obtained by using SrTiO₃（STO）as the transition layer,and[110]oriented SRO films were obtained by using La_0.7Sr_0.3MnO₃or yttrium（Y）-doped stable Zr O₂（YSZ）as the transition layer.（2）The thickness effect of SRO films under weak stress clamping was investigated SRO films of different thicknesses（3.5 nm-150 nm）were prepared under optimum growth conditions to investigate the electrical transport properties of different film thicknesses.The critical thickness for the transition from metallic to semiconductor state of[111]oriented films was found to be 8 nm,with the Curie temperature point increasing with increasing thickness and the films conforming to Fermi liquid behaviour at low temperatures.For the[110]oriented SRO films,the resistance of the films decreases and then increases with temperature from 62.5 nm to150 nm,and the semiconductor-metal transition point is between 70 K and 120 K.As the thickness of the films decreases the transition point gradually increases and the Curie temperature point（Tc）gradually decreases,and in a magnetic field the magnetoresistance reaches a minimum（-5.4%）when the film thickness reaches 50nm（-5.4%）.（3）Based on the excellent electrical conductivity of SRO films,the electrothermal properties of mica-based SRO films were studied and the effect of mica substrate thickness on the heating performance of SRO films was systematically investigated.For films of the same thickness,the thermal response and cooling time increase with increasing substrate thickness,and the saturation temperature also decreases with increasing substrate thickness for each voltage.At an output voltage of22 V,the SRO film heater achieves a heating temperature of 654°C.