论文标题
A级订购四倍的perovskite ymn $ _3 $ Mn $ _4 $ o $ $ $ _ {12} $
Evidence for centrosymmetry breaking and multiferroic properties in the A-site ordered quadruple perovskite YMn$_3$Mn$_4$O$_{12}$
论文作者
论文摘要
通过单晶X射线衍射，我们揭示了中央对称性的破坏，当时在小型a perovskite perovskite perovskite ymn $ _3 $ _3 $ _4 $ _4 $ _4 $ _4 $ o $ o $ o $ o $ o $ o $ o $ o $ _ $ o $ _ $ _ $ _ $ _} $ _} $ _} $ _} $ _} $ _} $ _3} $ _3} $ _3} $ _ 3} $ _3 $ _4 $ _3 $ _4 $ _4 $ _4 $ _4}时降低了t $ _s $ = 200 k的温度。该结果与已经报告的该化合物已经报告的所有数据一致，并解决了先前有关YTTrium位置的不一致。上层结构的特征是单晶图中的卫星反射出现，与以i为中心的伪伪 - 正常bombombig commensurate Supercell，$ a \ ob a \ sqrt {a_f} = 10.4352（7）$Å，$ b \ b \ b \ b \ b \ of 2b_f = 2b_f = 14.66049（9）$ 9） \ sqrt {c_f} = 10.6961（7）$ÅAND$β= 90.110（3）^\ circ $，其中F代表“基本”高温单元格（$ a_f \ a_f \ of c_f \ of c_f \ of c_f \ of c_f \ of约7.45 $Å，约7.45 $Å，$ b_f \ ob $ b_f \ of 7.34 $Å，$β和$ 90.毫无疑问，空间组是非极性的IA，因此允许材料中的非零极化。然后，我们详细研究了YMN $ _3 $ _3 $ _3 $ _4 $ o $ o $ _ {12} $的Pyrocurrent，Transport，介电以及DC和AC磁性。这些测量值清楚地表明了不同顺序之间的材料和相关性的几个临界温度：i）中心对称在高温下（t $ _s $ = 200k），ii），然后，b sites的远距离磁序发生在t $ _ {n，b} $ = 108 k的情况下，并在同一温度下，在同一温度下，在同一温度下，将复合的磁性变为纯净的dielctric dielctric dielctric。 iii）最后，残留的极化与t* = 70 k的磁异常同时稳定。我们提出YMN $ _3 $ _3 $ _4 $ _4 $ o $ o $ _ {12} $是一种特殊的磁性铁电磁性，极性状态由短距离磁性磁性顺序驱动。
By means of single-crystal X-ray diffraction we have revealed the breaking of centrosymmetry when lowering the temperature under T$_s$ = 200 K concomitantly with the setting of a commensurate superstructure in the small A-site quadruple perovskite YMn$_3$Mn$_4$O$_{12}$. This results is in agreement with all data already reported for this compounds and solve the previous inconsistency about the Yttrium position. The superstructure is characterized by the appearing of satellite reflections in the single crystal pattern, consistent with an I-centered pseudo-orthorhombic commensurate supercell with $a \approx \sqrt{a_F} = 10.4352(7)$ Å, $b \approx 2b_F = 14.6049(9)$ Å, $c \approx \sqrt{c_F} = 10.6961(7)$ Åand $β= 90.110(3)^\circ$, where F stands for the "fundamental" high-temperature cell ($a_F \approx c_F \approx 7.45$ Å, $b_F \approx 7.34$ Å, and $β\approx 90^\circ$). The space-group was unequivocally found to be Ia, which is non polar, thus allowing for a non-zero polarization in the material. We then have investigated in detail the pyrocurrent, transport, dielectric and the DC and AC magnetic properties of polycrystalline sample of YMn$_3$Mn$_4$O$_{12}$ over a wide temperature range. These measurements clearly highlight several critical temperatures in the material and correlation between the different orders: i) the centrosymmetry is broken at high temperature (T$_S$ = 200K), ii) then the long-range magnetic order of B-sites occurs at T$_{N,B}$ = 108 K and at this same temperature the compound enters in an insulating dielectric state. iii) Finally, a remnant polarization is stabilized concomitantly with a magnetic anomaly at T* = 70 K. We propose that YMn$_3$Mn$_4$O$_{12}$ is a peculiar magnetic ferroelectric in which the polar state is driven by short-range magnetic order.
