Lifting of xz/yz orbital degeneracy at the structural transition in detwinned FeSe
Lifting of xz/yz orbital degeneracy at the structural transition in detwinned FeSe
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DOI：
10.1103/physrevb.90.121111
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发表时间：
2014-09-29
影响因子：
3.7
通讯作者：
Ishizaka, K.
中科院分区：
文献类型：
--
作者：
Shimojima, T.;Suzuki, Y.;Ishizaka, K.
我们利用角分辨光电子能谱研究了超导 FeSe（T-c = 9K），其表现出四方-正交结构转变（T-s 类似于 90 K），没有任何反铁磁有序性。在解孪晶态下，布里渊区角处的d(yz)轨道带的能量位置比d(xz)的能量位置高50meV，表明其轨道顺序类似于NaFeAs和BaFe2As2族。轨道序的证据也出现在布里渊区中心的空穴带中。使用无应变样品精确测量的温度依赖性表明，轨道排序 (To) 的起始点非常接近 T-s，因此表明与 BaFe2As2 族相比，FeSe 中高于 T-s 的电子向列性要弱得多。
We study superconducting FeSe (T-c = 9K) exhibiting the tetragonal-orthorhombic structural transition (T-s similar to 90 K) without any antiferromagnetic ordering, by utilizing angle-resolved photoemission spectroscopy. In the detwinned orthorhombic state, the energy position of the d(yz) orbital band at the Brillouin zone corner is 50 meV higher than that of d(xz), indicating the orbital order similar to the NaFeAs and BaFe2As2 families. Evidence of orbital order also appears in the hole bands at the Brillouin zone center. Precisely measured temperature dependence using strain-free samples shows that the onset of the orbital ordering (To) occurs very close to T-s, thus suggesting that the electronic nematicity above T-s is considerably weaker in FeSe compared to BaFe2As2 family.