Boldyrev K N, Stanislavchuk T N, Sirenko A A, Kamenskyi D, Bezmaternykh L N, Popova M N
Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow 108840, Russia.
Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, USA.
Phys Rev Lett. 2017 Apr 21;118(16):167203. doi: 10.1103/PhysRevLett.118.167203. Epub 2017 Apr 18.
We report on a new effect caused by the electron-phonon coupling in a stoichiometric rare-earth antiferromagnetic crystal subjected to an external magnetic field, namely, the appearance of a nonzero gap in the spectrum of electronic excitations in an arbitrarily small field. The effect was registered in the low-temperature far-infrared (terahertz) reflection spectra of an easy-axis antiferromagnet PrFe_{3}(BO_{3}){4} in magnetic fields B{ext}∥c. Both paramagnetic and magnetically ordered phases (including a spin-flop one) were studied in magnetic fields up to 30 T, and two bifurcation points were observed. We show that the field behavior of the coupled modes can be successfully explained and modeled on the basis of the equation derived in the framework of the theory of coupled electron-phonon modes, with the same field-independent electron-phonon interaction constant |W|=14.8 cm^{-1}.
我们报道了在受到外磁场作用的化学计量比稀土反铁磁晶体中，由电子 - 声子耦合引起的一种新效应，即在任意小的磁场中电子激发谱中出现非零能隙。该效应在易轴反铁磁体PrFe₃(BO₃)₄在磁场Bₑₓₜ∥c下的低温远红外（太赫兹）反射光谱中被记录到。在高达30 T的磁场中研究了顺磁相和磁有序相（包括自旋翻转相），并观察到两个分岔点。我们表明，基于在耦合电子 - 声子模式理论框架中推导的方程，耦合模式的场行为可以得到成功解释和建模，其中场无关的电子 - 声子相互作用常数|W| = 14.8 cm⁻¹。
