Valsecchi Jacopo, Makowska Malgorzata G, Kim Youngju, Lee Seung Wook, Grünzweig Christian, Piegsa Florian M, Thijs Michel A, Plomp Jeroen, Strobl Markus
Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen, Switzerland and University of Geneva, Switzerland.
Photons for Engineering and Manufacturing Group, Paul Scherrer Institut, Villigen, Switzerland.
Phys Rev Lett. 2021 Feb 19;126(7):070401. doi: 10.1103/PhysRevLett.126.070401.
We have recently shown how a polarized beam in Talbot-Lau interferometric imaging can be used to analyze strong magnetic fields through the spin dependent differential phase effect at field gradients. While in that case an adiabatic spin coupling with the sample field is required, here we investigate a nonadiabatic coupling causing a spatial splitting of the neutron spin states with respect to the external magnetic field. This subsequently leads to no phase contrast signal but a loss of interferometer visibility referred to as dark-field contrast. We demonstrate how the implementation of spin analysis to the Talbot-Lau interferometer setup enables one to recover the differential phase induced to a single spin state. Thus, we show that the dark-field contrast is a measure of the quantum mechanical spin split analogous to the Stern-Gerlach experiment without, however, spatial beam separation. In addition, the spin analyzed dark-field contrast imaging introduced here bears the potential to probe polarization dependent small-angle scattering and thus magnetic microstructures.
我们最近展示了如何在塔尔博特-劳干涉成像中利用偏振光束，通过场梯度下的自旋相关微分相位效应来分析强磁场。在那种情况下，需要与样品场进行绝热自旋耦合，而在这里，我们研究的是非绝热耦合，它会导致中子自旋态相对于外部磁场发生空间分裂。这随后不会产生相位对比信号，而是导致干涉仪可见度的损失，即所谓的暗场对比。我们展示了如何在塔尔博特-劳干涉仪设置中实施自旋分析，从而能够恢复诱导到单个自旋态的微分相位。因此，我们表明暗场对比是量子力学自旋分裂的一种度量，类似于斯特恩-盖拉赫实验，但没有空间光束分离。此外，这里引入的自旋分析暗场对比成像具有探测偏振相关小角散射以及磁性微观结构的潜力。
