Magnetic field dependence of differential conductance in Kondo tunnel junctions
|關鍵字:||近藤效應;二雜質近藤效應;Kondo effect;Two-impurity Kondo effect|
We want to know the impurity moment of Two-impurity Kondo effect in the interface of the oxide layer about the influence of their array. Compare different about the ground state of the three phase of the Two-impurity Kondo model. We measure five tunneling junction that dope Y atom, and their ground state can correspond on three phase in 2IK. We change the direction and magnitude of magnetic field. To measure the differential conductance G(V,T) and magnetoresistance. Then we rise the temperature to 100K, after control magnetic field in 4T we cool temperature again to measure as before we measure. So we can discuss the different between zero-field-cooled and field-cooled. iii In fixed magnitude magnetic field we change the direction and we find the G(V,T) curve can be overlapping at B = 4T and B = -4T. For the compare between the zfc and fc, in our data can observe a small offset in the two G(V,T) curve. But the barrier of the tunneling junction is easy to change when we rise and cool the temperature, so we can’t clearly explain. And we fit the G(V,T) curve, to deduct the background. In fitting data we observe the overlapping peak between zfc and fc. At magnetoresistance, the sample with strong RKKY coupling have obvious magnetic hysteresis, but the sample that ground state is Kondo screened doesn’t have magnetic hysteresis. According to the experimental results, we know the impurity moment’s array and direction is uncorrelated to 2IK effect. At the ground state in Kondo screened doesn’t have magnetic hysteresis, and the ground state in QCP and RKKY have magnetic hysteresis. The magnetic hysteresis is bigger when the RKKY coupling is bigger.
|Appears in Collections:||Thesis|