标题: 复杂自适应物质研究---子计画二---复杂自适应磁电锰氧化物掺杂研究
Studies on Doped Complex Adaptive Magneto-Electric Manganites
作者: 庄振益
JUANG JENH-YIH
国立交通大学电子物理学系(所)
关键字: 复杂自适应物质;磁电多铁性材料;complex adaptive matters;multiferroic materials
公开日期: 2008
摘要: 本计画主要延续本研究群多年来在强关联系统之钙钛矿结构过
渡金属氧化物薄膜研究心得,并利用既有的薄膜制程机台与低温物
理量测系统,探讨掺杂钙钛矿结构锰氧化物的磁电多铁性质。尤其
是鉴于现今相关的研究,均仍集中在分辨这些复杂自适应物质中驱
动各种相形成的主要作用力的情况,我们认为适时的研究这些作用
力间有没有耦合?透过什么机制耦合?都是非常重要也必须得到解
答的基本问题。举例而言,直觉上,铁电性和结构扭曲造成之中心
对称偏移有关,而磁性则与局部自旋(local spin)相关。这两种看
似不相关的现象(或相),为何会共存在某些特定的材料?相的共存是
彼此竞争后的妥协,或是相互作用衍生的结果?他们之间是否可以
通过外加的perturbation 来诱发或改变彼此之间的相互作用?更有趣
的是,这二者在既有的所谓磁电多铁性材料中,相互间的作用似乎
还不够大到可以衍生功能性的应用。寻求一可以调变此一作用的机
制,显然是瞭解这类新颖复杂自适应物质的基本物理以及进一步衍
生新颖功能性元件的重要关键。本计画希望在未来三年内,利用我
们从庞磁阻效应研究所得到的经验,(即藉由掺杂镧锰氧反铁磁相,
引进可以在材料中漫游的非局域性载子,并进而衍生双交换作用
(double exchange)并导致材料从顺磁绝缘态转变为铁磁金属态的物
理),结合雷射镀膜技术对氧化物薄膜的成长与掺杂的优异性,有系统的经由掺杂磁电多铁性锰氧化物(如YMnO3, HoMnO3,TbMnO3
等),调变材料中不同作用力间的相互作用,以瞭解这类新颖复杂自
适应物质的基本物理以及进一步衍生新颖功能性元件。
This proposal is intended to extend our efforts and experiences
gained from the extensive investigations on the emergent behaviors
exhibited by the complex adaptive matters characterized by
strongly-correlated electrons, in particular, in the perovskite
oxides-related thin films over the past few years. We will utilize the
existent PLD system and low-temperature physical properties measuring
system to investigate emergent properties of the doped magneto-electric
multiferroic systems. In particular, in regarding to the fact that current
researches have been mainly focused on identifying the major
interactions that lead to the coexistence of multiferroic phases, we think
the following questions should be addressed, at least, equally
importantly. The questions are: “Is there a coupling between these
interactions?”“If yes, what is the dominant coupling mechanism?”
These are all the fundamental questions centered to the understanding of
these so-called “complex adaptive matters”that needed to be answered.
For instance, intuitively, ferroelectricity often originates from the
off-center asymmetry induced by structure distortion of the lattice,
whereas, magnetism is intimately related to the local spin structure. Why
would these two seemingly irrelevant phases (or phenomena) coexist in
the some particular materials? Is the coexistence of multiphases a result
of competition or compromise between different interactions among
different quasiparticles? Does the interplay between them can be somehow modulated by the external perturbations in a controllable way?
Even more interestingly from the application point of view, in most of
the current situations, the existent multiferroic materials appears to be
incapable of providing enough interplay between the ferroelectricity and
ferromagnetism (or anti-ferromagnetism) to put up viable functional
devices. It is thus very important to find a way of tuning these effects. It
will be a key to not only gain understanding on the physics behind the
complex adaptive nature of these materilas but also to give rise devices
with novel functionalities. There is a clue that these may all be
accomplished. Inspired from the experience in studying the colossal
magnetoresistive materials (which are also complex adaptive matters by
definition), doping can play a key role in changing the interactions. In
that case, the introduction of itinerant carriers by doping triggers the
double-exchange interaction between local spin moments and, in turn,
leads to a transition from paramagnetic insulator to ferromagnetic metal.
Similar physics is expected to prevail in these multiferroics, as well. We
intend, in the next three years, to combine the superior advantages of
pulsed laser deposition technique in growing stoichiometric oxide films
and achieving wide range doping and the experiences we had gained
previously, to systematically investigate the physical properties of doped
multiferroic systems, such as YMnO3, HoMnO3, TbMnO3. It is hoped
that by finding a way of tuning the interactions that lead to various
robust pahses existent in the system, the fundamental physics and
possibly novel device functionalties can be sucessfuly explored.
官方说明文件#: NSC95-2112-M009-035-MY3
URI: http://hdl.handle.net/11536/102013
https://www.grb.gov.tw/search/planDetail?id=1585798&docId=271795
显示于类别:Research Plans