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|標題:||Coexistence of Long-Range Orderings in the Ceramic Oxides|
|摘要:||Investigating the coexistence of the longrangeorderings in the ceramicoxides is the major focus in this proposal. Due to the specialty of the crystalstructure and the influence of the external physical parameters such as thetemperature, press, electric field and magnetic field, the longrangeorderingsincluding the superconductivity, ferromagnetism, antiferromagnetism, andferroelectricity will interplay each other. Based on the maturity of samplepreparation on the ceramic oxides in the past years, we are going to makeAxSr2LnCu3xO8.. (A =Ru, Mo; Ln =Rare Earth element; 0 ￡ x ￡ 2 );Ln1xMxMnO3(Ln = Rare Earth element, Tb; M = Ca, Sr, Ba; 0 ￡ x ￡ 1) samplesfor this study. Specimens will be prepared by the solidstatereaction techniquewith heat treatment. The lattice parameters, phase purity and chemicalcomposition of the specimens will be characterized by XrayPowder Diffraction(XRD) pattern and Energy Dispersive Spectroscopy (EDX).The microstructurewill be probed by the Scanning Electron Microscopy (SEM) and the TunnelingElectron Microscopy (TEM). The proposal will be divided into two parts. In thefirst part, we will investigate the competition between the magnetic ordering andthe superconductivity by systematically substituting Mo for part of the Cu andchanging the carrier concentration. A comparison of superconducting criticaltemperature (Tc) with the longrangemagneticorderingtemperature(Tm)among the ceramic oxides systems with different Mo or Ru concentration willbe made in order to study the mechanism of the superconductivity. In the secondpart, we will focus on the study of the coexistence of the longrangemagneticordering and ferroelectricity. We will investigate the electric, magnetic, andthermal properties over wide ranges of temperature (2K~350K) and magneticfield (0~±9T) by using the SQUID magnetometer and the Physical PropertyMeasurement System (PPMS). The Electron Spin Resonance will also be usedto sense the variation of the internal magnetic field under the phase transition.|
|Appears in Collections:||物理學系所|
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