Experimental confirmation of a p-p intraband gap in Sr 2 FeO 4
Experimental confirmation of a p-p intraband gap in Sr 2 FeO 4
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Sr 2 FeO 4 中p-p带内间隙的实验证实
DOI：
10.1103/physrevb.58.10283
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发表时间：
1998
影响因子：
3.7
通讯作者：
R. Taylor
中科院分区：
文献类型：
--
作者：
G. Rozenberg;A. Milner;M. Pasternak;G. Hearne;R. Taylor
对反铁磁性半导体${\mathrm{Sr}}_{2}{\mathrm{FeO}}_{4}({\mathrm{Fe}}^{4+}{，的电输运、磁性和结构性质进行了研究，并用电阻、铁谱和X射线衍射法对其进行了测量，得到了30 Gpa的压强。这项工作的相关结果是，半导体-金属相变发生在${P}_{C}\EnsureMATH{\sim}18(1)\mathm{GPA}，而$\mathm{Fe}(\mathm{IV})3d$磁矩在整个相变过程中保持不变。在最高压力为30 GPa时，晶胞的相对体积降至${V/V}_{0}\EnsureMath{\sim}0.82，且结构对称性未发生变化。在{P}_{C}及以上，磁超精细谱在自旋有序温度$TL{T}_{N}以下是明显的，它是由一个具有不可忽略的四极相互作用的单一组分组成的。$超精细场{(B}_{MATHROM{Hf}}=23\MATHROM{T})}和异构体位移在压力约为${P}_{C}时都没有发生剧烈或不连续的变化，这表明金属化后，{MATHROM{Fe}-}3D$电子态没有变化。这被认为是令人信服的实验证据，证明了配体能带流形中的p-p能隙是闭合的，因此是导致金属态发生的机制。
The electrical-transport, magnetic, and structural properties of the antiferromagnetic semiconductor ${\mathrm{Sr}}_{2}{\mathrm{FeO}}_{4}({\mathrm{Fe}}^{4+}{,d}^{4})$ have been probed by resistance, ${}^{57}\mathrm{Fe}$ M\"ossbauer spectroscopy, and x-ray-diffraction measurements to \ensuremath{\sim}30 GPa in a diamond-anvil cell. The pertinent results of this work are that a semiconductor-metal transition occurs at ${P}_{C}\ensuremath{\sim}18(1)\mathrm{GPa},$ while the $\mathrm{Fe}(\mathrm{IV})3d$ magnetic moments remain unaltered across the transition. To the highest pressure of 30 GPa, the relative volume of the unit cell decreases to ${V/V}_{0}\ensuremath{\sim}0.82,$ with no structural symmetry modification of the ${\mathrm{K}}_{2}{\mathrm{NiF}}_{4}$-type unit cell. At and above ${P}_{C},$ a magnetic hyperfine spectrum comprised of a single component with a non-negligible quadrupole interaction is evident below spin-ordering temperatures $Tl{T}_{N}.$ No drastic or discontinuous change occurs in both the hyperfine field ${(B}_{\mathrm{hf}}=23\mathrm{T})$ and isomer shift at pressures encompassing ${P}_{C},$ suggesting that the $\mathrm{Fe}\ensuremath{-}3d$ electronic state is unchanged upon metallization. This is considered compelling experimental evidence for closure of a $p\ensuremath{-}p$ gap within the ligand band manifold, and therefore is the mechanism responsible for the onset of a metallic state.