Tunable spin-state bistability in a spin crossover molecular complex
Tunable spin-state bistability in a spin crossover molecular complex
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DOI：
10.1088/1361-648x/ab1a7d
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发表时间：
2019-08-07
影响因子：
2.7
通讯作者：
Dowben, Peter A.
中科院分区：
文献类型：
--
作者：
Jiang, Xuanyuan;Hao, Guanhua;Dowben, Peter A.
本文研究了[Fe{H_2B（pz）（2）}（2）（bipy）]多晶薄膜在Al_2 O_3衬底上的自旋交叉（SCO）跃迁，其中pz =吡唑-1-基，bipy = 2，2 ′-联吡啶。对于几百nm厚的[Fe{H2 B（pz）（2）}（2）（bipy）]薄膜，磁性测量和X射线吸收光谱测量显示了SCO转变随温度的热滞后，而体相[Fe{H2 B（pz）（2）}（2）（bipy）]在157 K时转变为非滞后的。虽然这些薄膜中的微晶尺寸相似，但在较薄的薄膜中滞后变得更加突出，表明[Fe{H2 B（pz）（2）}（2）（bipy）]/Al 2 O3界面的显著影响。自旋态的双稳性，这可以从热滞后推断，直接观察到使用温度依赖的X-射线衍射，微晶的行为作为自旋态域的过渡期间共存。[Fe{H2 B（pz）（2）}（2）（bipy）]膜表面分子的自旋态与膜内分子的自旋态在热循环过程中的差异表明，分子间的协同效应和配位作用都与SCO跃迁的微扰有关.
The spin crossover (SCO) transitions at both the surface and over the entire volume of the [Fe{H2B(pz)(2)}(2) (bipy)] polycrystalline films on Al2O3 substrates have been studied, where pz = pyrazol-1-yl and bipy = 2,2'-bipyridine. For [Fe{H2B(pz)(2)}(2) (bipy)] films of hundreds of nm thick, magnetometry and x-ray absorption spectroscopy measurements show thermal hysteresis in the SCO transition with temperature, although the transition in bulk [Fe{H2B(pz)(2)}(2) (bipy)] occurs in a non-hysteretic fashion at 157K. While the size of the crystallites in those films are similar, the hysteresis becomes more prominent in thinner films, indicating a significant effect of the [Fe{H2B(pz)(2)}(2)(bipy)]/Al2O3 interface. Bistability of spin states, which can be inferred from the thermal hysteresis, was directly observed using temperature-dependent x-ray diffraction; the crystallites behave as spin-state domains that coexist during the transition. The difference between the spin state of molecules at the surface of the [Fe{H2B(pz)(2)}(2)(bipy)] films and that of the molecules within the films, during the thermal cycle, indicates that both cooperative (intermolecular) effects and coordination are implicated in perturbations to the SCO transition.