此篇論文主要是透過電傳輸性質來研究PdSn2半金屬系統的物理性質。在有外加磁場的情況下，載子會進行迴旋運動進而造成散射，這即是磁阻的來源。半古典的Kohler’s rule描述了載子在金屬材料中的傳輸與迴旋運動造成的散射相競爭的結果。意外的是PdSn2違反了Kohler’s rule所描述的機制，透過角解析光子激發能譜與能帶計算結果，我們得知PdSn2在溫度低於100 K左右費米面的拓墣性有改變。透過雙能帶模型模擬出靠近費米面的電子與電洞隨溫度之關係，我們發現PdSn2載子濃度大幅下降與遷移速率大幅上升所發生的溫度也是在100 K左右。高壓效應下的磁阻與霍爾效應也是我們感興趣的量測。藉由加壓來改變晶格常數，來對樣品的載子密度的壓力變化有更深的探討。

This thesis mainly focuses on the physical properties of semimetallic PdSn2 via electrical transport measurements. In the application of magnetic field charge carriers move along the cyclotron orbit and scatter, which is the source of magnetoresistance. A semi-classical Kohler's rule describes that magnetoresistance is proportional to how many cyclotron orbits the charge carrier can make before scattering. Surprisingly, this rule is violated in PdSn2 system. Angle-resolved photoemission (ARPES) measurement and band structure calculation reveal a change of Fermi surface topology below the temperature of 100 K in PdSn2. Via a two-band model, we realize how the density of electron and hole vary as a function of temperature. It turns out the temperature below which the carrier density suddenly decreases and the mobility increases is also around 100 K. We also conduct resistivity and Hall effect measurements under high pressure to study the pressure effect in comparison with the temperature-dependence transport results.

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