本文主要研究内容
作者徐钟麒（2019）在《铁基团簇点阵的磁耦合与输运性质》一文中研究指出：由于在电子与磁记录器件,生物医学治疗,微波吸收等各种领域有着不可替代的作用,磁性团簇一直是团簇科学中重要的研究对象。磁性团簇点阵的磁性被团簇的结构,多相的组成和团簇间的各种磁耦合作用所影响,磁性团簇间的磁交换耦合可以导致各种各样的磁序现象,这些性质对下一代纳米磁性和自旋电子器件的研发至关重要。另外,库仑阻塞磁电阻效应的研究也有广阔的应用前景,例如其所导致的极高的磁电阻对于磁记录器件磁头的开发意义重大。但是至今对于磁性团簇点阵中的磁耦合及电子输运机制仍然有大量不明确的地方。本文采用团簇束流沉积技术制备了不同结构参数的铁基磁性团簇阵列,对铁团簇点阵的磁性随温度,团簇尺寸及团簇覆盖率的变化及其与磁耦合的相关性,铁铬合金团簇点阵的磁性与磁耦合特性,铁团簇密集点阵的电子输运特性及磁电阻特性进行探讨。通过控制磁控等离子体气体聚集团簇源的缓冲气体流量的大小,制备了平均粒径从7.8 nm到15.9 nm的不同尺寸Fe团簇点阵。随着温度的升高,团簇呈现了清晰的铁磁性到超顺磁性的转变,阻塞温度约为100 KK。矫顽力和约化饱和磁化强度均随团簇尺寸的增大而增大。在较小的团簇尺寸时,团簇表面微弱氧化产生的反铁磁成分与铁团簇之间交换耦合形成的低温玻璃态削减了饱和磁化强度,而在大尺寸时多畴团簇的出现,使团簇饱和磁化强度趋于稳定。利用电导实时监测实现了对团簇覆盖率的精密控制。随着团簇覆盖率的增加,团簇间距变小,团簇间磁偶极耦合增加,导致饱和磁化强度增大,但团簇点阵的矫顽力随覆盖率无明显的变化。通过调节双靶团簇源溅射功率,制备了不同原子比例的Fe-Cr合金团簇。Cr原子比例较低时,Fe-Cr合金团簇以球形为主。随着Cr原子比例的增加,由于Cr的偏析引起bcc-Fe的晶格崎变而形成的类四方相团簇成为主体。其中Cr偏析(反铁磁)使得铁磁成分和反铁磁成分之间产生显著的交换偏置,增进了低温下的自旋玻璃态行为,导致Fe-Cr合金团簇矫顽力和偏置场下降。玻璃态升温弛豫导致在大于阻塞温度区域Fe-50%Cr合金团簇的零场冷(ZFC)与场冷(FC)曲线完全偏离,阻塞温度附近ZFC曲线变为平坦。其热稳定性及各向异性也都得以提高。Fe团簇密集点阵在低于120 K温度下出现很大的自旋库仑阻塞效应,20 K时电流阻塞阈值电压高达18.3 V,阻塞态电导较室温电导减小5到7个数量级,均远大于常规非磁性团簇点阵中纯静电库仑阻塞的相应值(～1 V,3-4个数量级)。自旋库仑阻塞和热激活输运相互竞争,使得Fe团簇密集点阵中的电子输运在低温下以变程跳跃输运为主导,高温时以热激活输运为主导,热激活输运在40 K-60 KK温度开始出现。团簇覆盖率越低,则热激活输运出现的温度越高,变程跳跃输运覆盖的温度更宽。在20 K-50 K温度的库仑阻塞区域,在Fe团簇密集点阵中观察到巨磁电阻,4T磁场下可达80%。通过对不同覆盖率样品的磁电阻比较,验证了在磁场条件下输运机制转变为了高阶共隧穿。在更低的温度下,还出现了有趣的正巨磁阻效应。
Abstract
you yu zai dian zi yu ci ji lu qi jian ,sheng wu yi xue zhi liao ,wei bo xi shou deng ge chong ling yu you zhao bu ke ti dai de zuo yong ,ci xing tuan cu yi zhi shi tuan cu ke xue zhong chong yao de yan jiu dui xiang 。ci xing tuan cu dian zhen de ci xing bei tuan cu de jie gou ,duo xiang de zu cheng he tuan cu jian de ge chong ci ou ge zuo yong suo ying xiang ,ci xing tuan cu jian de ci jiao huan ou ge ke yi dao zhi ge chong ge yang de ci xu xian xiang ,zhe xie xing zhi dui xia yi dai na mi ci xing he zi xuan dian zi qi jian de yan fa zhi guan chong yao 。ling wai ,ku lun zu sai ci dian zu xiao ying de yan jiu ye you an kuo de ying yong qian jing ,li ru ji suo dao zhi de ji gao de ci dian zu dui yu ci ji lu qi jian ci tou de kai fa yi yi chong da 。dan shi zhi jin dui yu ci xing tuan cu dian zhen zhong de ci ou ge ji dian zi shu yun ji zhi reng ran you da liang bu ming que de de fang 。ben wen cai yong tuan cu shu liu chen ji ji shu zhi bei le bu tong jie gou can shu de tie ji ci xing tuan cu zhen lie ,dui tie tuan cu dian zhen de ci xing sui wen du ,tuan cu che cun ji tuan cu fu gai lv de bian hua ji ji yu ci ou ge de xiang guan xing ,tie ge ge jin tuan cu dian zhen de ci xing yu ci ou ge te xing ,tie tuan cu mi ji dian zhen de dian zi shu yun te xing ji ci dian zu te xing jin hang tan tao 。tong guo kong zhi ci kong deng li zi ti qi ti ju ji tuan cu yuan de huan chong qi ti liu liang de da xiao ,zhi bei le ping jun li jing cong 7.8 nmdao 15.9 nmde bu tong che cun Fetuan cu dian zhen 。sui zhao wen du de sheng gao ,tuan cu cheng xian le qing xi de tie ci xing dao chao shun ci xing de zhuai bian ,zu sai wen du yao wei 100 KK。jiao wan li he yao hua bao he ci hua jiang du jun sui tuan cu che cun de zeng da er zeng da 。zai jiao xiao de tuan cu che cun shi ,tuan cu biao mian wei ruo yang hua chan sheng de fan tie ci cheng fen yu tie tuan cu zhi jian jiao huan ou ge xing cheng de di wen bo li tai xiao jian le bao he ci hua jiang du ,er zai da che cun shi duo chou tuan cu de chu xian ,shi tuan cu bao he ci hua jiang du qu yu wen ding 。li yong dian dao shi shi jian ce shi xian le dui tuan cu fu gai lv de jing mi kong zhi 。sui zhao tuan cu fu gai lv de zeng jia ,tuan cu jian ju bian xiao ,tuan cu jian ci ou ji ou ge zeng jia ,dao zhi bao he ci hua jiang du zeng da ,dan tuan cu dian zhen de jiao wan li sui fu gai lv mo ming xian de bian hua 。tong guo diao jie shuang ba tuan cu yuan jian she gong lv ,zhi bei le bu tong yuan zi bi li de Fe-Crge jin tuan cu 。Cryuan zi bi li jiao di shi ,Fe-Crge jin tuan cu yi qiu xing wei zhu 。sui zhao Cryuan zi bi li de zeng jia ,you yu Crde pian xi yin qi bcc-Fede jing ge qi bian er xing cheng de lei si fang xiang tuan cu cheng wei zhu ti 。ji zhong Crpian xi (fan tie ci )shi de tie ci cheng fen he fan tie ci cheng fen zhi jian chan sheng xian zhe de jiao huan pian zhi ,zeng jin le di wen xia de zi xuan bo li tai hang wei ,dao zhi Fe-Crge jin tuan cu jiao wan li he pian zhi chang xia jiang 。bo li tai sheng wen chi yu dao zhi zai da yu zu sai wen du ou yu Fe-50%Crge jin tuan cu de ling chang leng (ZFC)yu chang leng (FC)qu xian wan quan pian li ,zu sai wen du fu jin ZFCqu xian bian wei ping tan 。ji re wen ding xing ji ge xiang yi xing ye dou de yi di gao 。Fetuan cu mi ji dian zhen zai di yu 120 Kwen du xia chu xian hen da de zi xuan ku lun zu sai xiao ying ,20 Kshi dian liu zu sai yu zhi dian ya gao da 18.3 V,zu sai tai dian dao jiao shi wen dian dao jian xiao 5dao 7ge shu liang ji ,jun yuan da yu chang gui fei ci xing tuan cu dian zhen zhong chun jing dian ku lun zu sai de xiang ying zhi (～1 V,3-4ge shu liang ji )。zi xuan ku lun zu sai he re ji huo shu yun xiang hu jing zheng ,shi de Fetuan cu mi ji dian zhen zhong de dian zi shu yun zai di wen xia yi bian cheng tiao yue shu yun wei zhu dao ,gao wen shi yi re ji huo shu yun wei zhu dao ,re ji huo shu yun zai 40 K-60 KKwen du kai shi chu xian 。tuan cu fu gai lv yue di ,ze re ji huo shu yun chu xian de wen du yue gao ,bian cheng tiao yue shu yun fu gai de wen du geng kuan 。zai 20 K-50 Kwen du de ku lun zu sai ou yu ,zai Fetuan cu mi ji dian zhen zhong guan cha dao ju ci dian zu ,4Tci chang xia ke da 80%。tong guo dui bu tong fu gai lv yang pin de ci dian zu bi jiao ,yan zheng le zai ci chang tiao jian xia shu yun ji zhi zhuai bian wei le gao jie gong sui chuan 。zai geng di de wen du xia ,hai chu xian le you qu de zheng ju ci zu xiao ying 。
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论文详细介绍
论文作者分别是来自南京大学的徐钟麒，发表于刊物南京大学2019-07-02论文，是一篇关于铁基团簇点阵论文,团簇束流沉积论文,交换耦合论文,自旋玻璃论文,自旋库仑阻塞论文,南京大学2019-07-02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，资料来自南京大学2019-07-02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：铁基团簇点阵论文; 团簇束流沉积论文; 交换耦合论文; 自旋玻璃论文; 自旋库仑阻塞论文; 南京大学2019-07-02论文;