High-field phase diagram of the Haldane-gap antiferromagnet $Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)$
High-field phase diagram of the Haldane-gap antiferromagnet $Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)$
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霍尔丹带隙反铁磁体$Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)$的高场相图
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发表时间：
2004
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通讯作者：
Y. Takano
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作者：
H. Tsujii;Z. Honda;B. Andraka;K. Katsumata;Y. Takano
本文用比热测量方法测定了准一维$S=$1海森堡反铁磁体$Ni（C_5H_{14} N_2）_2N_3（PF_6）$的磁相图，温度为150 mK，磁场为32 T。当沿自旋链方向施加沿着磁场时，在H_{c2}约14$ T处出现一个新相。对于已知的场诱导有序相，由于最低温度比以前的工作提高了四倍，精确地确定了零温临界场$H_c$附近有序温度的幂律指数。结果进行了比较的基础上的玻色-爱因斯坦凝聚的三重态激发的预测。氘取代氢被发现稍微减少链间交换。
We have determined the magnetic phase diagram of the quasi-one-dimensional $S=$ 1 Heisenberg antiferromagnet $Ni (C_5 H_{14} N_2)_2 N_3 (PF_6)$ by specific heat measurements to 150 mK in temperature and 32 T in magnetic field. When field is applied along the spin-chain direction, a new phase appears at $H_{c2}\approx 14$ T. For the previously known phases of field-induced order, accurate determination is made of the power-law exponents of the ordering temperature near the zero-temperature critical field $H_c$, owing to the four-fold improvement of the minimum temperature over the previous work. The results are compared with the predictions based on the Bose-Einstein condensation of triplet excitations. Substituting deuterium for hydrogen is found to slightly reduce the interchain exchange.