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智科眼: 双语看懂新科研
量子物理学 5956
In(In) 2005,(2005,) condensed(凝聚) matter(问题) physicists(物理学家) Charles(查尔) Kane(Kane) and() Eugene(尤金) Mele(迈乐) considered(考虑) the fate(命运) of(of) graphene(石墨烯) at(at) low temperatures(低温).(.) Their(他们) work(工作) led(led) to(to) the discovery(发现) of(of) a(一种) new() state of matter(物质状态) dubbed(被称为) a(a) "(")topological(拓扑) insulator(绝缘体),"(,") which(which) would() usher(引入) in(in) a(a) new() era(时代) of(of) materials science(材料科学).(.)
"A("A) topological(拓扑) insulator(绝缘体) is() a(一种) material(材料) that() is() an(an) insulator(绝缘体) in(in) its() interior(内部) but() is(is) highly() conducting(导电) on(on) its(它的) surface(表面),"(,") said() UC(加州大) Santa() Barbara(巴巴拉) assistant(助理) physics(物理学) professor(教授) Andrea(Andrea) Young(青年).(.) In(In) two(two)-()dimensions(),(,) an(an) ideal(理想) topological(拓扑) insulator(绝缘体) would() have(具有) "(")ballistic(弹道)"(") conductance(电导) at(at) its() edges(边缘),(,) Young(青年) explained(解释说),(,) meaning(意味) that() electrons(电子) traveling through(穿过) the region(区域) would(would) encounter(遇到) zero() resistance(电阻).(.)
Ironically(讽刺意味),(,) while(虽然) Kane(Kane) and() Mele(迈乐)'s('s) work(工作) would() lead to(导致) the discovery(发现) of(of) topological(拓扑) insulating(绝缘) behavior(行为) in(in) a(a) wide(广泛) variety(各种) of(of) materials(材料),(,) their(他们) original() prediction(预测)—of(—of) a(a) topological(拓扑) insulator(绝缘体) in(in) graphene(石墨烯)()has(具有) remained() unrealized(未实现).(.)
At(At) the heart() of(of) the trouble(问题) is() spin(自旋)-()orbit(轨道) coupling(耦合)—a(—a) weak(微弱) effect(作用) in(in) which(其中) the spin(自旋) of(of) the electron(电子) interacts(相互作用) with(with) its(与其) orbital motion(轨道运动) aroun(aroun) the nucleus(核心).(.) Critical(关键) to(to) all(所有) topological(拓扑) insulators(绝缘体),(,) spin-orbit coupling(自旋轨道耦合) is() exceptionally(特别) weak() in(in) graphene(石墨烯),(,) so(非常) that() any(任何) topological(拓扑) insulating(绝缘) behavior(行为) is(is) drowned(淹没) out(out) by(by) other(other) effects(影响) arising(产生) from(from) the surface(表面) on(on) which(which) the graphene(石墨烯) is(is) supported(支持).(.)
"(")The weak(微弱) spin(自旋)-()orbit(轨道) coupling(耦合) in(in) graphene(石墨烯) is(is) a(a) great() pity(怜悯),"(,") said() postdoctoral(博士后) researcher(研究员) Joshua(约书亚) Island(),(,) because(因为) in(in) practice(实践) things(事情) haven(没有)'t('t) really(真正) worked out(研究出) that() well() for(for) topological(拓扑) insulators(绝缘体) in(in) two(two) dimensions().(.) "(")The two dimensional(二维) topological(拓扑) insulators(绝缘体) known(已知) to(to) date(目前为止) are() disordered(无序) and(并且) not() very() easy(容易) to(to) work(工作) with(with),"(,") Island() said().(.) The conductance(电导) at(at) the edges(边缘) tends(趋于) to(to) diminish() rapidly(迅速) with(with) the distance(距离) the electrons(电子) travel(),(,) suggesting(表明) it() is(is) far() from(from) ballistic(弹道).(.) Realizing(实现) a(一种) topological(拓扑) insulator(绝缘体) in(in) graphene(石墨烯),(,) an(an) otherwise(否则) highly(非常) perfect(完美) two dimensional(二维) material(材料),(,) could(可以) provide(提供) a(a) basis(基础) for(for) low()-()dissipation(耗散) ballistic(弹道) electrical circuits(电路) or(或者) form(形成) the material(材料) substrate(衬底) for(for) topologically(拓扑) protected(保护) quantum(量子) bits().(.)
Now(现在),(,) in(in) work() published(发表) in(in) the journal(期刊) Nature(本质),(,) Island(),(,) Young(青年) and() their(他们) collaborators(合作者) have() found(找到) a(a) way(方法) to(to) turn() graphene(石墨烯) into(into) a(a) topological(拓扑) insulator(绝缘体) (TI).((TI).) "(")The goal(目标) of(of) the project(项目) was() to(to) increase(增加) or() enhance(增强) the spin-orbit coupling(自旋轨道耦合) in(in) graphene(石墨烯),"(,") lead(lead) author(作者) Island() said(),(,) adding(补充) that() attempts(尝试) have(have) been(been) made(made) over(over) the years(多年) with(with) limited() success(成功).(.) "A("A) way(方法) to(to) do() this(这样) is() to(to) put() a(一种) material(材料) that(that) has(具有) a(一种) very(非常) large() spin-orbit coupling(自旋轨道耦合) in(in) close(紧密) proximity(接近) with(with) the graphene(石墨烯).(.) The hope(希望) was(was) that(that) by(通过) doing() that(that) your(你的) graphene(石墨烯) electrons(电子) will() take(take) on(on) this(这种) property(特性) of(of) the underlying(底层) material(材料),"(,") he() explained(解释).(.)
The material(材料) of(of) choice(选择)?(?) After(After) studying(研究) several(几种) possibilities(可能性),(,) the researchers(研究人员) settled(定居) on(on) a(一种) transition metal(过渡金属) dichalcogenide(二硫) (TMD),((TMD),) consisting(组成) of(of) the transition metal(过渡金属) tungsten() and() the chalcogen(硫属) selenium().(.) Similar(类似) to(to) graphene(石墨烯),(,) tungsten() diselenide(二硒) comes() in(in) two-dimensional(二维) monolayers(单层),(,) bound(结合) together(一起) by(通过) van(van) der(范德) Waals() forces(),(,) which(which) are() relatively(相对较) weak() and() distance(距离)-()dependent(依赖) interactions(相互作用) between(between) atoms(原子) or() molecules(分子).(.) Unlike(不同) graphene(石墨烯),(,) however(然而),(,) the heavier atoms(重原子) of(of) the TMD(TMD) lead to(导致) stronger(更强) spin-orbit coupling(自旋轨道耦合).(.) The resulting(产生) device(器件) feature(特征)'s('s) graphene(石墨烯)'s('s) ballistic(弹道) electron(电子) conductance(电导) imbued(灌输) with(with) the strong() spin-orbit coupling(自旋轨道耦合) from(from) the nearby(附近) TMD(TMD) layer().(.)
"We("We) did(确实) see(看到) a(a) very(非常) clear(明显) enhancement(增强) of(of) that(that) spin(旋转)-()orbit(轨道) coupling(耦合),"(,") Island() said().(.)
"By("By) adding(添加) spin-orbit coupling(自旋轨道耦合) of(of) just(just) the right(恰当) type(类型),(,) Joshua(约书亚) was(was) able(能够) to(to) find(发现) that(that) this() in fact(实际上) leads to(导致) a(一个) new() phase(阶段) which(which) is(is) almost(几乎) topologically(拓扑) insulating(绝缘),"(,") Young(青年) said().(.) In(In) the original() idea(想法),(,) he() explained(解释说),(,) the topological(拓扑) insulator(绝缘体) consisted(组成) of(of) a(a) monolayer(单层) of(of) graphene(石墨烯) with(with) a(a) strong() spin-orbit coupling(自旋轨道耦合).(.)
"We("We) had to(必须) use(使用) a(a) trick(技巧) only() available(可用) in(in) graphene(石墨烯) multilayers(多层) to(to) create(创建) the right(正确) type(类型) of(of) spin-orbit coupling(自旋轨道耦合),"(,") Young(青年) explained(解释) about(about) their(他们) experiment(实验),(,) which(which) used(使用) a(a) graphene(石墨烯) bilayer(双层).(.) "(")And() so(所以) you() get(得到) something(东西) that(that) approximates(近似于) two(两个) topological(拓扑) insulators(绝缘体) stacked(叠加) on(on) top(top) of(of) each other(彼此)."(.") Functionally(功能上),(,) however(然而),(,) Island()'s('s) device(器件) performs(执行) as(as) well() as(as) other(其他) known(已知) 2-D(2-D) topological(拓扑) insulators(绝缘体)()the all(所有)-()important(重要) edge(边缘) states(状态) propagate(传播) for(for) at least(至少) several() microns(微米),(,) much(much) longer() than(than) in(in) other(其他) known(已知) TI(TI) materials(材料).(.)
Furthermore(此外),(,) according to(根据) Young(青年),(,) this(这项) work(工作) is(is) one(一个) step(一步) closer(距离) to(to) building(建造) an(an) actual(实际) topological(拓扑) insulator(绝缘体) with(with) graphene(石墨烯).(.) "(")Theoretical(理论) work(工作) has(has) since(since) shown(表明) that(that) a(a) graphene(石墨烯) trilayer(三层),(,) fabricated(制造) in(in) the same(同样) way(方式),(,) would() lead to(导致) a(a) true(真正) topological(拓扑) insulator(绝缘体)."(.")
Most() importantly(重要),(,) the devices(器件) realized(实现) by(by) Island() and() Young(青年) can(可以) be(be) easily(轻松) tuned(调谐) between(between) a(a) topological(拓扑) insulating(绝缘) phase() and() a(a) regular(常规) insulator(绝缘体),(,) which(which) does(does) not() have(具有) conducting(导电) edge(边缘) states(状态).(.)
"(")You() can(可以) route(路径) these(这些) perfect(完美) conductors(导体) around(around) wherever(任何地方) you() want(想要),"(,") he() said(),(,) "(")And() that()'s('s) something(事情) nobody(没有人)'s('s) been(been) able(能够) to(to) do() with(with) other(other) materials(材料)."(.")

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