We report a layered ternary selenide BaPt₄Se₆ featuring sesqui-selenide Pt₂Se₃ layers sandwiched by Ba atoms. The Pt₂Se₃ layers in this compound can be derived from the Dirac-semimetal PtSe₂ phase with Se vacancies that form a honeycomb structure. This structure results in a Pt (VI) and Pt (II) mixed-valence compound with both PtSe₆ octahedra and PtSe₄ square net coordination configurations. Temperature-dependent electrical transport measurements suggest two distinct anomalies: a resistivity crossover, mimic to the metal-insulator (M-I) transition at ~150 K, and a resistivity plateau at temperatures below 10 K. The resistivity crossover is not associated with any structural, magnetic, or charge order modulated phase transitions. Magnetoresistivity, Hall, and heat capacity measurements concurrently suggest an existing hidden state below 5 K in this system. Angle-resolved photoemission spectroscopy measurements reveal a metallic state and no dramatic reconstruction of the electronic structure up to 200 K.

我们报告了一种层状三元硒化物 BaPt ₄ Se _6，其特征是倍半硒化物 Pt ₂ Se ₃层被 Ba 原子夹在中间。该化合物中的 Pt ₂ Se ₃层可以衍生自 Dirac-半金属 PtSe ₂相，具有形成蜂窝结构的 Se 空位。这种结构产生了 Pt (VI) 和 Pt (II) 混合价化合物，同时具有 PtSe ₆八面体和 PtSe ₄方网协调配置。与温度相关的电传输测量表明存在两种不同的异常：电阻率交叉，模拟~150 K 时的金属-绝缘体 (MI) 转变，以及温度低于 10 K 时的电阻率平台。电阻率交叉与任何结构无关，磁性或电荷顺序调制相变。磁阻、霍尔和热容量测量同时表明该系统中存在低于 5 K 的隐藏状态。角度分辨光电子能谱测量显示出金属状态，并且在高达 200 K 时没有显着的电子结构重建。