文章信息/Info

Title:

A Typical Magnetic Tunnel Junction Material and�ぁ糐Z〗Effects of Tunnel Magneto�睷esistance

作者:

韓秀峰; 劉厚方; 張佳; 師大偉; 劉東屏; �へS家峰; 魏紅祥; 王守國; 詹文山

(中國科學院物理研究所，北京 100000)

Author(s):

HAN Xiufeng;  LIU Houfang;  ZHANG Jia;  SHI Dawei;  LIU Dongping; FENG Jiafeng;  WEI Hongxiang;  WANG Shouguo;  ZHAN Wenshan

（Institutute of Physics of Chinese Academy of Sciences，Beijing 100000，China）

關鍵詞:

巨磁電阻效應; 隧穿磁電阻效應; 磁性隧道結; 第一性原理計算; 自旋轉移力矩效應; 庫侖阻塞磁電阻; 磁隨機存儲器

DOI:

10.7502/j.issn.1674-3962.2013.06.02

文獻標志碼:

A

摘要:

典型的磁性隧道結是“三明治”結構，即由上下兩個鐵磁電極以及中間厚度為1 nm量級的絕緣勢壘層構成。當外加磁場使兩鐵磁電極的磁矩由平行態向反平行態翻轉時，隧穿電阻會發生低電阻態向高電阻態的轉變。自從1995年發現室溫隧穿磁電阻(TMR)以來，非晶勢壘的AlO���玿��磁性隧道結在磁性隨機存儲器(MRAM)和磁硬盤磁讀頭(Read Head)中得到了廣泛的應用，2007年室溫下其磁電阻比值可達到80%。下一代高速、低功耗、高性能的自旋電子學器件的發展，迫切需要更高的室溫TMR比值和新型的調制結構。2001年通過第一性原理計算發現：由于MgO(001)勢壘對不同對稱性的自旋極化電子具有自旋過濾(Spin Filter)效應， 單晶外延的Fe(001)/MgO(001)/Fe(001)磁性隧道結的TMR比值可超過1 000%，隨后2004年在單晶或多晶的MgO磁性隧道結中獲得室溫約200%的TMR比值，2008年更是在贗自旋閥結構CoFeB/MgO/CoFeB磁性隧道結中獲得高達604%的室溫TMR比值。伴隨著新勢壘材料的不斷發現和各種磁性隧道結結構的優化，共振隧穿和自旋依賴的庫侖阻塞磁電阻等新效應以及磁性傳感器、磁性隨機存儲器和自旋納米振蕩器及微波檢測器等新器件逐漸成為科學和工業界所關注的研究與應用熱點。對磁性隧道結(MTJ)材料及其器件應用研究和進展進行了簡要介紹。��

Abstract:

A typical magnetic tunnel junction (MTJ) consists of a thin insulating layer (a tunnel barrier)， sandwiched by two ferromagnetic electrode layers. When the relative magnetic configuration of both ferromagnetic electrode layers changes from parallel state to anti�瞤arallel state with external magnetic field， the resistance of MTJ would become high from low， exhibiting tunnel magneto�瞨esistance (TMR) due to spin�瞕ependent electron tunnelling. Amorphous AlO���玿�� barrier MTJs were extensively studied and have been used in magneto�瞨esistance random access memory (MRAM) and read heads of hard disk drives， since the discovery of room�瞭emperature TMR in 1995. However， the spin electronic devices development of the next�瞘eneration high�瞫peed， low�瞤ower�瞔onsumption and high�瞤erformance need much higher TMR ratio and a novel structure. In 2001， the first�瞤rinciple calculation predicted that the TMR ratio of epitaxial Fe (001)/MgO (001)/Fe (001) MTJs would be over 1 000%， due to spin filter effect of MgO barrier for different symmetry spin polarized electron. In 2004 TMR ratios of about 200% were obtained in MTJs with a single�瞔rystal MgO (001) barrier or a textured MgO (001) barrier. In 2008， the TMR ratio of 604% has been reported in pseudo�瞫pin�瞯alve MTJs with core structure of CoFeB/MgO/CoFeB. Recently， Quantum well (QW) resonances tunneling and spin�瞕ependent Coulomb blockade magneto�瞨esistance (CBMR) effect in MgO�瞓arrier MTJs were proposed and demonstrated in theories and experiments. Magnetic sensors， MRAM， spin nano�瞣scillator and microwave detector based on MTJs have attracted attention of electron science and devices. In the paper we briefly introduced the investigation and development of magnetic tunnel junction material and its device applications.