多鐵材料Co3-xCuxTeO6的強自旋阻挫效應;Strong spin frustrations in multiferroic Co3-xCuxTeO6

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/74255

Title:	多鐵材料Co3-xCuxTeO6的強自旋阻挫效應;Strong spin frustrations in multiferroic Co3-xCuxTeO6
Authors:	陳家圳;Chen, Chia-Tsun
Contributors:	物理學系
Keywords:	多鐵材料;阻挫效應;multiferroic;frustration
Date:	2017-07-14
Issue Date:	2017-10-27 13:39:52 (UTC+8)
Publisher:	國立中央大學
Abstract:	近年來，對於新型Te金屬氧化物M3TeO6系統，其中M為第一行過渡金屬的研究文獻如雨後春筍般接踵而至，此系統材料擁有非常顯著且豐富的相變物理特性，因此科學家們提出大量的實驗方法、理論與現象來描述該系統，例如簡單對稱性自旋(simple commensurate spin)、複合不對稱性自旋(complex incommensurate spin)、自發極化與磁場驅動極化。　　此篇論文將討論M為Co與Cu以不同摻雜比例之物理特性變化，首先利用固態反應法製程，製備出Co3-xCuxTeO6樣品，其中x =0.06、0.12、0.18、1與2，經過X光繞射儀分析後，確認該材料對稱性主要為Monoclinic C2/c與Cubic Ia3 ̅，而隨著x值的增加觀察到Cubic Ia3 ̅對稱性比例越多。由交流磁化率對溫度趨勢圖中，五組樣品皆呈現反鐵磁特性與自旋玻璃特性。透過中子繞射確認了x = 1之樣品鈷與銅比例為0.69：0.31，在低溫時觀察到兩較明顯之(100)與(110)的短程有序磁結構，亦在moment transfer q = 0.915 Å-1 觀察到Magnon能量峰值為0.08 meV的中子非彈性散射現象。　　Co3-xCuxTeO6樣品擁有著複雜又豐富的磁性、電性與磁電耦合等物理特性，此篇論文主要研究不同銅參雜比例的Co3-xCuxTeO6樣品的磁結構、磁特性與鐵電特性的交互作用。 ;Many novel physical behaviors have recently been identified in novel-metal tellurates M3TeO6, where M is a first-row transition metal. Simple commensurate (CM) and complex incommensurate (ICM) spin structures, spontaneous and magnetic-field-driven electrical polarization have all been detected. Very fruitful physical properties that associated with three phase transitions have been observed in Co3TeO6. The monoclinic Co3TeO6 has been characterized as a type-II multiferroic, where CM and ICM spin structures have been identified to associated with separate atomic layers, magnetic incommensurability changes regularly and largely with temperature, the development of ferroelectricity links closely to local domain atomic non-uniformity, and a significant amount of electronic charges shifts to regions where local crystallographic distortions and/or asymmetry appear through ferroelectric transition. There are two crystallographic distinct Co layers in Co3TeO6. It has been demonstrated that the Co ions in the honeycomb web link to the ferroelectricity greatly better than those Co spins in the separated zigzag chains. Cu-doping to replace the Co ions in the zigzag chains (the x = 1 sample) or in the honeycomb web (the x = 2 sample) can provide in depth information on the strength of the coupling of the zigzag chains or honeycomb web to ferroelectricity. On the other hand, studies made on the magnetic and electric properties of Co3TeO6 are still very limited. An antiferromagnetic transition was observed below 60 K. This anomaly is believed to be associated with the mixed Cu+/Cu2+ valence in the Cu3TeO6 ceramics. The magnetic and electric properties and the interplay between the electrics and magnetic degree of freedom in Cu-doped Co3-xCuxTeO6 will be again complex and fruitful. We aim to study the magnetic structure and interplay between ferroelectric and magnetic parameters in Cu-doped Co3-xCuxTeO6 with x = 0.06, 0.12, 0.18, 1 and 2.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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