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Title: | 鉀銠氧單晶之異常磁傳輸特性研究 Anomalous Magnetotransport Characteristics of Single Crystal KxRhO2 |
Authors: | Jia-Wei Huang 黃家瑋 |
Advisor: | 王立民(Li-Min Wang) |
Keyword: | 助熔劑成長法,鉀銠氧,電阻-溫度相依性,拓樸霍爾效應,非共平面自旋, flux growth method,KxRhO2,topological hall effect,temperature dependence of resistivity,non-coplanar spins, |
Publication Year : | 2018 |
Degree: | 碩士 |
Abstract: | 本研究以助熔劑成長法合成單晶鉀銠氧(KxRhO2)並且用能量散射光譜儀做元素分析,計算出樣品中鉀含量x的值。我們合成出兩種不同鉀含量的樣品- K0.52RhO2、K0.42RhO2並研究其電性、磁性以及霍爾效應。我們使用X射線繞射儀來量測其c軸晶格長度,K0.52RhO2、K0.42RhO2的c軸晶格長度分別為12.26 Å與12.28 Å。
接著我們試著把KxRhO2浸在鹽酸中試著讓水分子進入RhO2層之間,試著改變其結構看是否會出現超導現象。在水分子進入結構之後,其c軸晶格常數增加為13.67 Å,其晶格常數的改變來自於水分子進入結構中,導致c軸晶格常數增加。 在電性量測過程中,我們發現了電阻率與溫度間特別的關係。在K0.52RhO2與K0.42RhO2中低溫時出現了電阻率與溫度平方關係,高溫時電阻率與溫度則呈現1.5次方關係,其轉變溫度分別為177.46 K與168.53 K;加入水分子的樣品則在低溫即出現了電阻率與溫度1.5次方關係,當高溫時則轉變為電阻率與溫度呈線性關係,此一特別的物理現象可以鍵長漲落效應解釋之。 最後我們根據期刊Phys. Rev. Lett. 116, 256601(2016) 文章其理論預期非共面的自旋會出現拓樸霍爾效應,因此我們做了K0.52RhO2單晶拓樸霍爾效應的量測與計算,並觀察到類似拓樸霍爾效應的現象。 We synthesised single KxRhO2 crystals with a flux growth method and determine the composition of potassium with Energy-dispersive X-ray spectroscopy (EDS). We have synthesised two samples with different composition of potassium, K0.52RhO2 and K0.42RhO2, and study the magnetotransport properties and Hall effect of samples. We measured the lattice parameter of c-axis with X-ray Diffraction (XRD), and the lattice parameters of c-axis of K0.52RhO2 and K0.42RhO2 are 12.26 Å and 12.28 Å, respectively. Then we tried to make H2O insert into the structure of KxRhO2 and wonder whether the KxRhO2 become superconducting. The lattice parameter of c-axis increased from 12.26 Å to 13.67 Å when the water was inserted into the RhO2 layer. The increasing in parameter of c-axis is due to the insertion of H2O molecules into the KxRhO2 structure. In electrical measurements, we found a special relationship between resistivity and temperature. In K0.52RhO2 and K0.42RhO2, the resistivity ρ(T) is proportional to T2 at low temperatures and is proportional to T1.5 at high temperatures. The transition temperature of K0.52RhO2 and K0.42RhO2 are 177.46 K and 168.53 K, respectively. This special phenomenon can be explained by locally cooperative bond-length fluctuation. The resistivity of samples containing the water is found to be proportional to the T1.5 at low temperatures and be proportional to the T1 at high temperatures. Finally, based on the article of Phys. Rev. Lett. 116, 256601(2016),” Predicted Quantum Topological Hall Effect and Noncoplanar Antiferromagnetism K0.5RhO2”, which theoretically predicted that the topological hall effect can occur in non-coplanar spins, we did the measurement and calculation of topological hall effect in K0.52RhO2 single crystals. A topological-hall-effect-like phenomenon was observed. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/21951 |
DOI: | 10.6342/NTU201803508 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 應用物理研究所 |
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