本文選題：Cr基超導(dǎo)　切入點(diǎn)：Mn基超導(dǎo)　出處：《陜西師范大學(xué)》2015年碩士論文

【摘要】：最近發(fā)現(xiàn)的高壓下CrAs和MnP的超導(dǎo)電性,使CrAs和MnP分別成為Cr基和Mn基第一個(gè)超導(dǎo)體化合物,這一發(fā)現(xiàn)在超導(dǎo)領(lǐng)域引起了巨大的反響。CrAs和MnP的體超導(dǎo)電性出現(xiàn)在一個(gè)反鐵磁量子臨界點(diǎn)附近,暗示了非常規(guī)的超導(dǎo)配對(duì)機(jī)制。然而很多揭示超導(dǎo)微觀機(jī)制的實(shí)驗(yàn)手段很難在高壓下進(jìn)行。因此嘗試用化學(xué)摻雜的方法探索兩個(gè)體系中更多可能的超導(dǎo)電性,實(shí)現(xiàn)Cr基和Mn基化合物的常壓超導(dǎo),對(duì)研究CrAs和MnP的非常規(guī)超導(dǎo)電性非常重要。本文的研究工作在此基礎(chǔ)上展開。本文首次利用助熔劑法成功制備出摻雜的CrAs和MnP0.8B0.2單晶樣品,并對(duì)CrAs1-xPx和MnP0.8B0.2單晶樣品進(jìn)行了系統(tǒng)的低溫物性研究,最后與CrAs和MnP高壓下的實(shí)驗(yàn)結(jié)果進(jìn)行比較。本文主要由以下三部分構(gòu)成：第一部分首先介紹了CrAs單晶的基本物性和高壓下CrAs的超導(dǎo)電性。隨后首次報(bào)道了CrAs1-xPx單晶樣品的電阻率和比熱實(shí)驗(yàn)數(shù)據(jù)。低溫下正常態(tài)電阻率和電子比熱系數(shù)γ的行為,說明在臨界摻雜量x=0.05附近存在一個(gè)量子臨界點(diǎn),此時(shí)CrAs的長(zhǎng)程磁有序已被完全壓制掉。這與CrAs高壓下的行為相似。但在2K以上沒有觀測(cè)到超導(dǎo)。第二部分首先介紹了高壓誘導(dǎo)的MnP超導(dǎo)電性。隨后首次報(bào)道了MnP0.8B0.2單晶樣品的電阻率、比熱和磁化率數(shù)據(jù)。Mn0.8B0.2單晶樣品的磁矩很小,表現(xiàn)出強(qiáng)的磁各向異性。在低溫下,MnP0.8B0.2中存在很強(qiáng)的磁阻效應(yīng)。MnP0.8B0.2在100K以下處于傾斜反鐵磁態(tài)或螺旋磁有序態(tài)。MnP0.8B0.2的低溫正常態(tài)電阻率與MnP加壓4-6GPa時(shí)的行為非常相似。德拜溫度和MnP基本一樣,而態(tài)密度相比MnP有明顯增加。第三部分總結(jié)目前所做的工作,提出未解決的問題和未來的可行性研究方向。
[Abstract]:The recently discovered superconductivity of CrAs and MnP at high pressure makes CrAs and MnP the first superconductor compounds based on Cr and mn respectively. This discovery has caused great repercussions in the field of superconductivity. CRAs and MnP's bulk superconductivity appears near an antiferromagnetic quantum critical point. However, many experimental methods to reveal the microcosmic mechanism of superconductivity are difficult to carry out at high pressure. Therefore, we try to explore more possible superconductivities in the two systems by chemical doping. The realization of atmospheric superconductivity of Cr-based and Mn-based compounds is very important for the study of the unconventional superconductivity of CrAs and MnP. Based on this work, the doped CrAs and MnP0.8B0.2 single crystal samples were successfully prepared by flux method for the first time in this paper. The low temperature physical properties of CrAs1-xPx and MnP0.8B0.2 single crystal samples were studied systematically. In the first part, the basic physical properties of CrAs single crystal and the superconductivity of CrAs at high pressure are introduced, and then the CrAs1-xPx single crystal is reported for the first time. Experimental data on resistivity and specific heat of samples. Behavior of electrical resistivity and electron specific heat coefficient 緯 in normal state at low temperature. It is shown that there is a quantum critical point near the critical doping amount x0. 05. At this time, the long range magnetic order of CrAs has been completely suppressed. This is similar to the behavior of CrAs at high pressure. However, no superconductivity has been observed above 2K. In the second part, the superconductivity of MnP induced by high pressure is first introduced. Then MnP0.8B0.2 is reported for the first time. Resistivity of single crystal sample, The specific heat and magnetic susceptibility data. Mn0.8B0.2 single crystal sample has very small magnetic moment, The magnetoresistive effect of MnP0.8B0.2 is very strong at low temperature. The resistivity of MnP0.8B0.2 in the tilted antiferromagnetic state or spiral magnetically ordered state. MNP 0.8B 0.2 is very similar to the behavior of MnP pressurized 4-6GPa at low temperature. Debye temperature is basically the same as MnP, The density of states is much higher than that of MnP. The third part summarizes the work done at present and puts forward the unsolved problems and the future feasibility research direction.
【學(xué)位授予單位】：陜西師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM26

【共引文獻(xiàn)】

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