论文标题
非kramers中的量子promagnetism稀土氧化物：单斜$ \ rm pr_2ti_2o_7 $
Quantum paramagnetism in a non-Kramers rare-earth oxide: Monoclinic $\rm Pr_2Ti_2O_7$
论文作者
论文摘要
到目前为止，关于$ \ rm a_2b_2o_7 $单斜层层状孔孔的磁性鲜为人知，该perovskites替换了$ r_a/r_b> 1.78 $的旋转冰冰冰球结构。 We show that high quality monoclinic Pr$_2$Ti$_2$O$_7$ single crystals with a three-dimensional network of non-Kramers Pr$^{3+}$ ions that interact through edge-sharing super-exchange interactions, form a singlet ground state quantum paramagnet that does not undergo any magnetic phase transitions down to at least 1.8 K. The chemical phase stability, structure, and magnetic properties of the使用X射线衍射，传输电子显微镜和磁化测量结果研究了分层的钙钛矿Pr $ _2 $ _2 $ _2 $ o $ $ _7 $。 pr $ _2 $ _2 $ _ {2+x} $ o $ $ _7 $（$ -0.16 \ leq x \ leq 0.16 $）的多晶样品的合成，表明与Pr $ _2 $ _2 $ _2 $ _2 $ $ _7 $ _7 $ sto phresse secters secterss secterss secters sectersssections sectersssectionss secterss secters secters sectersssectionssssectionsssections pr sectorse sectorse sectionssssectialssssections pr $ _2 $ _7 pr $ _ {2/3} $ tio $ _3 $和ORTHORHOMBIC PARSE pr $ _4 $ ti $ _9 $ _9 $ o $ _ {24} $和pr $ _2 $ tio $ _5 $。在PR $ _2 $ _2 $ _2 $ o $ _7 $多数阶段中，没有观察到现场无序（填充和反塞）或空缺缺陷的迹象。据报道，据报道，据报道，旅行溶剂浮动区（TSFZ）方法的高结构质量，化学计量学单晶的生长程序。单晶Pr $ _2 $ _2 $ _2 $ _2 $ o $ _7 $的热磁性测量表明，我们与低对称性水晶电场环境相关联，将$ 2J+1 = 9 $ 1 = 9 $ fold spinere spinere spin-ecormated Pr $ nike n隔离pr $^$ andement $^3 $} $^3+}分配给3+} 3+} 3+} 3+}^3+。低$ t $的各向异性温度独立的van-vleck易感性。一个小的各向同性居里术语与0.96（2）\％非相互作用pr $^{4+} $杂质相关。
Little is so far known about the magnetism of the $\rm A_2B_2O_7$ monoclinic layered perovskites that replace the spin-ice supporting pyrochlore structure for $r_A/r_B>1.78$. We show that high quality monoclinic Pr$_2$Ti$_2$O$_7$ single crystals with a three-dimensional network of non-Kramers Pr$^{3+}$ ions that interact through edge-sharing super-exchange interactions, form a singlet ground state quantum paramagnet that does not undergo any magnetic phase transitions down to at least 1.8 K. The chemical phase stability, structure, and magnetic properties of the layered perovskite Pr$_2$Ti$_2$O$_7$ were investigated using x-ray diffraction, transmission electron microscopy, and magnetization measurements. Synthesis of polycrystalline samples with the nominal compositions of Pr$_2$Ti$_{2+x}$O$_7$ ($-0.16 \leq x \leq 0.16$) showed that deviations from the Pr$_2$Ti$_2$O$_7$ stoichiometry lead to secondary phases of related, structures including the perovskite phase Pr$_{2/3}$TiO$_3$ and the orthorhombic phases Pr$_4$Ti$_9$O$_{24}$ and Pr$_2$TiO$_5$. No indications of site disordering (stuffing and anti-stuffing) or vacancy defects were observed in the Pr$_2$Ti$_2$O$_7$ majority phase. A procedure for growth of high-structural-quality, stoichiometric single crystals of Pr$_2$Ti$_2$O$_7$ by the traveling solvent floating zone (TSFZ) method is reported. Thermo-magnetic measurements of single-crystalline Pr$_2$Ti$_2$O$_7$ reveal an isolated singlet ground state that we associate with the low symmetry crystal electric field environments that split the $2J+1=9$-fold degenerate spin-orbital multiplets of the four differently coordinated Pr$^{3+}$ ions into 36 isolated singlets resulting in an anisotropic temperature independent van-Vleck susceptibility at low $T$. A small isotropic Curie term is associated with 0.96(2)\% non-interacting Pr$^{4+}$ impurities.
