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Spin injection phenomena in oxide he...

Chen, Zhiyun.

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Spin injection phenomena in oxide heterostructures.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Spin injection phenomena in oxide heterostructures./
作者:	Chen, Zhiyun.
面頁冊數:	152 p.
附註:	Source: Dissertation Abstracts International, Volume: 63-06, Section: B, page: 2944.
Contained By:	Dissertation Abstracts International63-06B.
標題:	Engineering, Electronics and Electrical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3055556
ISBN:	9780493711447

Spin injection phenomena in oxide heterostructures.
Chen, Zhiyun.

Spin injection phenomena in oxide heterostructures. - 152 p.

Source: Dissertation Abstracts International, Volume: 63-06, Section: B, page: 2944.

Thesis (Ph.D.)--University of Maryland, College Park, 2002.

This dissertation mainly concerns two fervently pursued areas: spintronics and oxide materials. Spintronic devices, devices utilizing the spin of electrons, have broad potential applications such as magnetic sensors and magnetic nonvolatile memories. In these devices, spin-polarized current, electrical current predominately composed of one type of spin, is employed. To study materials which can supply highly spin-polarized current is crucial for this type of devices.

ISBN: 9780493711447Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

Spin injection phenomena in oxide heterostructures.
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245 1 0 $a Spin injection phenomena in oxide heterostructures.
300 $a 152 p.
500 $a Source: Dissertation Abstracts International, Volume: 63-06, Section: B, page: 2944.
500 $a Chair: T. Venkatesan.
502 $a Thesis (Ph.D.)--University of Maryland, College Park, 2002.
520 $a This dissertation mainly concerns two fervently pursued areas: spintronics and oxide materials. Spintronic devices, devices utilizing the spin of electrons, have broad potential applications such as magnetic sensors and magnetic nonvolatile memories. In these devices, spin-polarized current, electrical current predominately composed of one type of spin, is employed. To study materials which can supply highly spin-polarized current is crucial for this type of devices.
520 $a In recently rediscovered colossal magnetoresistance (CMR) manganites, conducting electrons have been shown, both theoretically and experimentally, to be highly spin-polarized. A prototype spin injection device based on CMR material and high Tc superconductor (HTSC) was realized in this thesis. Devices built on Nd0.7Sr0.3MnO 3(NSMO)/LaAlO3(LAO)/YBa2Cu3O7- x(YBCO) trilayer have shown the ability to suppress the critical current of the superconducting YBCO by the spin-polarized current injection from the ferromagnetic NSMO layer. Current gain varies from 3 to 8, much larger than the spin-unpolarized injection in the LaNiO 3(LNO)/LAO/YBCO structure. This device can serve as a switch or even a superconductor transistor.
520 $a There is evidence showing that physical properties of the CMR surface deviate from the bulk CMR properties. For example: X-ray magnetic circular dichroism (XMCD) study of La0.7Sr0.3MnO3(LSMO) surface layer has revealed rapid decay of surface spin polarization with increasing temperature. XMCD study of capped LSMO surface showed further decrease in the near surface spin polarization. Thus understanding the novel physical properties, especially the transport properties, at the CMR/HTSC interface is critical for the optimization of spin injection devices.
520 $a The zero bias conductance peak (ZBCP), intrinsically associated with an ab-plane d-wave superconductor was observed at our Ag/YBCO and LNO/YBCO interfaces. However, in our transport study of an LSMO/YBCO interface, the ZBCP was not present at low temperature. This absence of ZBCP is interpreted as the suppression of ZBCP by the spin-polarized current from the LSMO film. It is the first report of such a phenomenon. The ZBCP observed at higher temperature is due to the rather swift decrease of the LSMO surface spin polarization with increasing temperature. This decay of the spin polarization of the conducting electrons at the LSMO surface was observed for the first time by our group. Theoretical simulation yields an LSMO surface spin polarization of 78% at 1.6 K. This value agrees with the result obtained using point contact measurement. It decreases to about 68% at 40 K.
520 $a Understanding other materials with high spin polarization, such as CrO 2, may also lead to new spintronic devices. Therefore transport study of a CrO2/Ag/YBCO interface was also carried out using a flip-chip configuration. It showed that at the CrO2 surface, spin polarization is quite stable up to 80 K, a temperature up to which our measurement could be performed due to the Tc limit of YBCO. Therefore CrO2 is a promising candidate for applications at higher temperatures.
590 $a School code: 0117.
650 4 $a Engineering, Electronics and Electrical. $3 626636
690 $a 0544
710 2 0 $a University of Maryland, College Park. $3 657686
773 0 $t Dissertation Abstracts International $g 63-06B.
790 1 0 $a Venkatesan, T., $e advisor
790 $a 0117
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3055556