Pyrochlore 結構本身具有幾何受挫性，加上擁有強磁矩 Ho3+ 間的磁偶極交互作用，使許多 Ho-pyrochlores 具有自旋冰的特性。另一方面，具備5d 電子軌域的 Ir-pyrochlore 預測會有電子-電子關聯和自旋軌道耦合的交互作用，近期受到關注，因此本文將呈現 Ho2Ir2O7 在直流磁化率、交流磁化率、比熱和中子彈性散射實驗上的結果，藉由直流磁化率的測量確認在 140 K 下 Ir4+ 的有序排列，磁亂度的分析顯示 Ho3+ 和 Ir4+ 之間的作用，崩解自旋冰基態本為 2進2出的短距有序結構。而中子繞射和比熱測量更進一步透露分別在18 K 和 75 K ~ 100 K 之間Ho-pyrochlores 形成 <111> 和垂直 <111> 形式的長距磁序排列，前者即為全進全出的磁結構。

Recently, there is a growing interest in iridated-pyrochlore compounds primarily due to possess 5d-electron elements. Among these compounds, Ho2Ir2O7 is also the spin ice candidate. We will present the experimental results of magnetization, heat capacity, and neutron diffraction on Ho2Ir2O7. The magnetization and resistivity measurements confirm the Ir order temperature at ~140 K. The accumulated entropy of Rln2 released below 2 K shows the symmetry of the two-in-two-out spin ice ground state is destroyed by the interactions between Ho ions and Ir ions. The neutron diffraction results reveal two type of the polarization on Ho ions. One is the <111> type (i. e. the all-in-all-out state), the other one is the perpendicular <111> type. And they respectively start to polarize at 18 K and between 75 K and 100 K.

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