Photocurrent suppression near antiferromagnetic transition in an organic Mott-insulator β′-(BEDT-TTF)(TCNQ) crystal
Photocurrent suppression near antiferromagnetic transition in an organic Mott-insulator β′-(BEDT-TTF)(TCNQ) crystal
复制标题
有机莫特绝缘体 β′-(BEDT-TTF)(TCNQ) 晶体中反铁磁转变附近的光电流抑制
DOI：
10.1002/pssb.201350409
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
M. Sakai and H. Mino
中科院分区：
文献类型：
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作者：
T. Ginoza;T. Shinohara;M. Sakai and H. Mino
我们测量了有机Mott绝缘体β′-（bis（ethylenedithio）-tetrathiafulvalene）（7，7，8，8-tetracyanoquinodimethane）（BEDT-TTF）（TCNQ）晶体在c轴和b轴沿着施加的偏压高达12 V时光电流的温度依赖性。使用波长为405 nm的半导体激光器作为光源。我们观察到，随着偏置电压的增加，光电流开始流动的温度下降到16 K，接近BEDT-TTF的反铁磁（AF）转变温度（TN= 20 K）。这一结果表明AF转变在抑制光生载流子传导中起着重要作用。强束缚的holon-doublon团簇的产生，预计将存在于AF自旋序态，被确定为负责的光电流抑制的因素之一。在TN以上，可以确认，通过改变偏置电压的极性，光生电子和空穴都可以作为光电流被检测到。
We measured the temperature dependence of the photocurrent in an organic Mott‐insulator β′‐(bis(ethylenedithio)‐tetrathiafulvalene)(7,7,8,8‐tetracyanoquinodimethane) (BEDT‐TTF)(TCNQ) crystal with applied bias voltage along thec‐ andb‐axis up to 12 V. A semiconductor laser with a wavelength of 405 nm was used as the light source. We observed that with increasing bias voltage, the temperature at which the photocurrent starts to flow decreases down to 16 K, near the antiferromagnetic (AF) transition temperature of BEDT‐TTF (TN= 20 K). This result indicates that the AF transition plays an important role in the suppression of photogenerated carrier conduction. The creation of strongly bound holon–doublon clusters, which are expected to exist in the AF spin order states, is identified as one of the factors responsible for the photocurrent suppression. Above theTN, it was confirmed that both the photogenerated electron and hole can be comparably detected as the photocurrent by changing the polarity of the bias voltage.