本文主要研究内容
作者祝钦清（2019）在《新型狄拉克材料的合成与物性研究》一文中研究指出：近十年来,狄拉克材料由于其在低能激发态中所具有的无质量Dirac电子而吸引了人们广泛的关注。在这类材料中人们观察到了许多新奇的物理现象,比如巨磁阻效应、超高的载流子迁移率、量子霍尔效应等。尤其是这些奇异的物理性质甚至能在室温环境下观测到,因此使得这类材料在电子器件应用中具有广泛的潜在价值。本论文的主要工作集中在三个方面:(1)合成高品质的EuMn0.8Sb2单晶,并对其输运性质和磁性质进行系统研究,发现其具有巨磁阻和巨磁热电势效应;(2)合成高品质的SrAgAs单晶,并对其磁阻和SdH振荡进行系统研究,证明了SrAgAs中存在二维Dirac费米子;(3)合成高品质的EuAg4As2单晶,并对其输运性质和磁性质进行系统研究,揭示其低温时Eu磁矩的自旋翻转相变以及与之相关的奇异磁电阻行为。获得的主要创新性成果如下:(1)我们详细研究了具有Mn离子缺陷的斜方晶系的EuMn008Sb2晶体的结构、输运性质和磁性质。结果表明,面内电阻率ρbc和面间电阻率ρa随温度的变化在整个测量温度范围内(2K-300K)均表现为金属性行为,这一点不同于之前报道的无Mn离子缺陷的EuMnSb2晶体。在T=2K,B=9T时,观测到一个较大的正磁电阻(约127%,在300K,约25%),这个正磁阻可以由两部分磁阻构成——普通能带的半经典磁阻和Dirac费米子的量子极限线性磁阻。我们还在低温下观察到超高迁移率的载流子(分别为5050cm2/Vs和1450cm2/Vs)和巨大的磁热电势效应。24K和10K处出现的两个电阻率扭曲,分别对应于Eu离子磁矩的反铁磁有序和磁矩倾斜。我们的实验结果让人们重新理解了 EuMn0.8Sb2的内在性质,并证明了 EuMn0.8Sb2化合物中Dirac费米子的存在。(2)通过自助熔方法,我们成功合成了 SrAgAs单晶,通过X射线衍射方法和EDX分别确认了其结构和化学成分。然后我们对其输运性质进行了系统测量。我们发现,其低温下磁阻在9T磁场下就出现明显的SdH振荡,快速傅里叶变换结果得到振荡频率为92.6T,通过L-K公式拟合,我们得到其载流子有效质量为0.088me,并且具有Berry相位0.92π,同时我们的霍尔测量结果表明其载流子类型为空穴型,在T=2K时浓度为4.6×1019Ccm-3,以此得到的迁移率高达1067cm2/Vs,所有这些结果均支持SrAgAs载流子中Dirac电子的存在,最后,我们也测量了转角磁阻,结果显示SrAgAs具有二维费米面。通过这些研究,我们证明了 SrAgAs中具有准二维的Dirac费米子。(3)通过自助熔方法合成EuAg4As2单晶,通过X射线衍射方法和EDX分别确认了其结构和化学成分。在得到高品质单晶样品的基础上,我们对其进行了系统的输运性质和磁性质测量。磁性质测量表明,低场下(μ0H=0.1T)EuAg4As2随着温度的降低分别在T=15K和T=9K经历两个磁相变,分别对应Eu磁矩的短程反铁磁有序和长程反铁磁有序,并且相变温度随着磁场的增大而减小。低温时的磁阻(MR)测量表明,随着磁场增大磁阻先增大后减小,甚至出现负磁阻的现象,对应EuAg4As2中的Eu磁矩随着外磁场的增加从低场的长程反铁磁有序态过渡到短程反铁磁有序态,直至强场时的铁磁态。最后,我们根据不同磁场和不同温度下的磁性质和输运性质测量结果,提出了 EuAg4As2的相图。
Abstract
jin shi nian lai ,di la ke cai liao you yu ji zai di neng ji fa tai zhong suo ju you de mo zhi liang Diracdian zi er xi yin le ren men an fan de guan zhu 。zai zhe lei cai liao zhong ren men guan cha dao le hu duo xin ji de wu li xian xiang ,bi ru ju ci zu xiao ying 、chao gao de zai liu zi qian yi lv 、liang zi huo er xiao ying deng 。you ji shi zhe xie ji yi de wu li xing zhi shen zhi neng zai shi wen huan jing xia guan ce dao ,yin ci shi de zhe lei cai liao zai dian zi qi jian ying yong zhong ju you an fan de qian zai jia zhi 。ben lun wen de zhu yao gong zuo ji zhong zai san ge fang mian :(1)ge cheng gao pin zhi de EuMn0.8Sb2chan jing ,bing dui ji shu yun xing zhi he ci xing zhi jin hang ji tong yan jiu ,fa xian ji ju you ju ci zu he ju ci re dian shi xiao ying ;(2)ge cheng gao pin zhi de SrAgAschan jing ,bing dui ji ci zu he SdHzhen dang jin hang ji tong yan jiu ,zheng ming le SrAgAszhong cun zai er wei Diracfei mi zi ;(3)ge cheng gao pin zhi de EuAg4As2chan jing ,bing dui ji shu yun xing zhi he ci xing zhi jin hang ji tong yan jiu ,jie shi ji di wen shi Euci ju de zi xuan fan zhuai xiang bian yi ji yu zhi xiang guan de ji yi ci dian zu hang wei 。huo de de zhu yao chuang xin xing cheng guo ru xia :(1)wo men xiang xi yan jiu le ju you Mnli zi que xian de xie fang jing ji de EuMn008Sb2jing ti de jie gou 、shu yun xing zhi he ci xing zhi 。jie guo biao ming ,mian nei dian zu lv ρbche mian jian dian zu lv ρasui wen du de bian hua zai zheng ge ce liang wen du fan wei nei (2K-300K)jun biao xian wei jin shu xing hang wei ,zhe yi dian bu tong yu zhi qian bao dao de mo Mnli zi que xian de EuMnSb2jing ti 。zai T=2K,B=9Tshi ,guan ce dao yi ge jiao da de zheng ci dian zu (yao 127%,zai 300K,yao 25%),zhe ge zheng ci zu ke yi you liang bu fen ci zu gou cheng ——pu tong neng dai de ban jing dian ci zu he Diracfei mi zi de liang zi ji xian xian xing ci zu 。wo men hai zai di wen xia guan cha dao chao gao qian yi lv de zai liu zi (fen bie wei 5050cm2/Vshe 1450cm2/Vs)he ju da de ci re dian shi xiao ying 。24Khe 10Kchu chu xian de liang ge dian zu lv niu qu ,fen bie dui ying yu Euli zi ci ju de fan tie ci you xu he ci ju qing xie 。wo men de shi yan jie guo rang ren men chong xin li jie le EuMn0.8Sb2de nei zai xing zhi ,bing zheng ming le EuMn0.8Sb2hua ge wu zhong Diracfei mi zi de cun zai 。(2)tong guo zi zhu rong fang fa ,wo men cheng gong ge cheng le SrAgAschan jing ,tong guo Xshe xian yan she fang fa he EDXfen bie que ren le ji jie gou he hua xue cheng fen 。ran hou wo men dui ji shu yun xing zhi jin hang le ji tong ce liang 。wo men fa xian ,ji di wen xia ci zu zai 9Tci chang xia jiu chu xian ming xian de SdHzhen dang ,kuai su fu li xie bian huan jie guo de dao zhen dang pin lv wei 92.6T,tong guo L-Kgong shi ni ge ,wo men de dao ji zai liu zi you xiao zhi liang wei 0.088me,bing ju ju you Berryxiang wei 0.92π,tong shi wo men de huo er ce liang jie guo biao ming ji zai liu zi lei xing wei kong xue xing ,zai T=2Kshi nong du wei 4.6×1019Ccm-3,yi ci de dao de qian yi lv gao da 1067cm2/Vs,suo you zhe xie jie guo jun zhi chi SrAgAszai liu zi zhong Diracdian zi de cun zai ,zui hou ,wo men ye ce liang le zhuai jiao ci zu ,jie guo xian shi SrAgAsju you er wei fei mi mian 。tong guo zhe xie yan jiu ,wo men zheng ming le SrAgAszhong ju you zhun er wei de Diracfei mi zi 。(3)tong guo zi zhu rong fang fa ge cheng EuAg4As2chan jing ,tong guo Xshe xian yan she fang fa he EDXfen bie que ren le ji jie gou he hua xue cheng fen 。zai de dao gao pin zhi chan jing yang pin de ji chu shang ,wo men dui ji jin hang le ji tong de shu yun xing zhi he ci xing zhi ce liang 。ci xing zhi ce liang biao ming ,di chang xia (μ0H=0.1T)EuAg4As2sui zhao wen du de jiang di fen bie zai T=15Khe T=9Kjing li liang ge ci xiang bian ,fen bie dui ying Euci ju de duan cheng fan tie ci you xu he chang cheng fan tie ci you xu ,bing ju xiang bian wen du sui zhao ci chang de zeng da er jian xiao 。di wen shi de ci zu (MR)ce liang biao ming ,sui zhao ci chang zeng da ci zu xian zeng da hou jian xiao ,shen zhi chu xian fu ci zu de xian xiang ,dui ying EuAg4As2zhong de Euci ju sui zhao wai ci chang de zeng jia cong di chang de chang cheng fan tie ci you xu tai guo du dao duan cheng fan tie ci you xu tai ,zhi zhi jiang chang shi de tie ci tai 。zui hou ,wo men gen ju bu tong ci chang he bu tong wen du xia de ci xing zhi he shu yun xing zhi ce liang jie guo ,di chu le EuAg4As2de xiang tu 。
论文参考文献
论文详细介绍
论文作者分别是来自杭州师范大学的祝钦清，发表于刊物杭州师范大学2019-10-16论文，是一篇关于狄拉克材料论文,磁热电势论文,振荡论文,磁阻论文,杭州师范大学2019-10-16论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自杭州师范大学2019-10-16论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
标签：狄拉克材料论文; 磁热电势论文; 振荡论文; 磁阻论文; 杭州师范大学2019-10-16论文;