Superconducting and magnetic phase diagram of RbEuFe4As4 and CsEuFe4As4 at high pressure
Superconducting and magnetic phase diagram of RbEuFe4As4 and CsEuFe4As4 at high pressure
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DOI：
10.1103/physrevb.98.014518
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发表时间：
2018-05
影响因子：
3.7
通讯作者：
D. Jackson;D. VanGennep;W. Bi;Dongzhou Zhang;P. Materne;Yi Liu;G. Cao;S. Weir;Y. Vohra;J. Hamlin
中科院分区：
文献类型：
--
作者：
D. Jackson;D. VanGennep;W. Bi;Dongzhou Zhang;P. Materne;Yi Liu;G. Cao;S. Weir;Y. Vohra;J. Hamlin
最近发现的\mathrm{Cs}){\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$化合物表现出超导(${T}_{c}\ensuremath{\sim}35\phantom{\rule{0.16em}{0ex}}\mathrm{K}$)和铁磁性(${T}_{m}\ensuremath{\sim}15\phantom{\rule{4pt}{0ex}}\mathrm{K}$).的不同寻常的组合在高达$\ensuremath{\sim}30\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$.的压力下，我们进行了一系列的X射线衍射、交流磁化率、直流磁化强度和电阻率测量我们发现，在$d{T}_{m}/dP\ensuremath{\sim}1.7\phantom{\rule{4pt}{0ex}}\mathrm{K}/\mathrm{GPa}$和$1.5\phantom{\rule{4pt}{0ex}}\mathrm{K}/\mathrm{GPa}$的初始速率下，超导电性的起始被压力单调地抑制，而磁相变在${\mathm{RbEuFe}}_{4}{\mathm{As}}_{4}$和${\mathm{CsEuFe}_{4}{\mathm{as}}_{4}$，分别进行了分析。在接近7 GPa时，${T}_{c}$开始与${T}_{m}$具有可比性。在较高的压力下，大块超导电性的信号逐渐消失。室温X射线衍射测量表明，在$\ensuremath{\sim}10\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$($\mathm{RbEuFe})和$\ensuremath{\sim}12\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$(${\mathm{CsEuFe}})开始从四方(T)相转变为半坍塌-四方(Hct)相。{4}{\mathm{as}}_{4}$)。在相对适中的压力下调谐{T}_c}和{T}_m}的能力突出地表明，\mathrm{Cs}){\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$化合物是研究超导和铁磁性相互作用的理想体系。
The recently discovered $(\mathrm{Rb},\mathrm{Cs}){\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$ compounds exhibit an unusual combination of superconductivity (${T}_{c}\ensuremath{\sim}35\phantom{\rule{0.16em}{0ex}}\mathrm{K}$) and ferromagnetism (${T}_{m}\ensuremath{\sim}15\phantom{\rule{4pt}{0ex}}\mathrm{K}$). We have performed a series of x-ray diffraction, ac magnetic susceptibility, dc magnetization, and electrical resistivity measurements on both ${\mathrm{RbEuFe}}_{4}{\mathrm{As}}_{4}$ and ${\mathrm{CsEuFe}}_{4}{\mathrm{As}}_{4}$ to pressures as high as $\ensuremath{\sim}30\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$. We find that the superconductivity onset is suppressed monotonically by pressure while the magnetic transition is enhanced at initial rates of $d{T}_{m}/dP\ensuremath{\sim}1.7\phantom{\rule{4pt}{0ex}}\mathrm{K}/\mathrm{GPa}$ and $1.5\phantom{\rule{4pt}{0ex}}\mathrm{K}/\mathrm{GPa}$ for ${\mathrm{RbEuFe}}_{4}{\mathrm{As}}_{4}$ and ${\mathrm{CsEuFe}}_{4}{\mathrm{As}}_{4}$, respectively. Near 7 GPa, ${T}_{c}$ onset and ${T}_{m}$ become comparable. At higher pressures, signatures of bulk superconductivity gradually disappear. Room-temperature x-ray diffraction measurements suggest the onset of a transition from tetragonal (T) to a half-collapsed-tetragonal (hcT) phase at $\ensuremath{\sim}10\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$ (${\mathrm{RbEuFe}}_{4}{\mathrm{As}}_{4}$) and $\ensuremath{\sim}12\phantom{\rule{4pt}{0ex}}\mathrm{GPa}$ (${\mathrm{CsEuFe}}_{4}{\mathrm{As}}_{4}$). The ability to tune ${T}_{c}$ and ${T}_{m}$ into coincidence with relatively modest pressures highlights $(\mathrm{Rb},\mathrm{Cs}){\mathrm{EuFe}}_{4}{\mathrm{As}}_{4}$ compounds as ideal systems to study the interplay of superconductivity and ferromagnetism.