Melnikov M.YDolgopolov V.TShashkin A.AHuang S.-HLiu C.WKravchenko S.V.CHEE-WEE LIU2021-09-022021-09-02201700218979https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038364808&doi=10.1063%2f1.4991545&partnerID=40&md5=e9b83daedc36e160d695c27b4e138d20https://scholars.lib.ntu.edu.tw/handle/123456789/580644We find an unusual anisotropy of the inplane field magnetoresistance with higher resistance in the parallel orientation of the field, B∥, and current, I, in ultra-high mobility SiGe/Si/SiGe quantum wells. The anisotropy depends on the orientation between the inplane field and the current relative to the crystallographic axes of the sample, and is a consequence of the ridges on the quantum well surface. For the parallel or perpendicular orientations between current and ridges, a method of converting the magnetoresistance measured at B∥ into the one measured at I∥B∥ is suggested and is shown to yield results that agree with the experiment. ? 2017 Author(s).Anisotropy; Crystallography; Magnetoresistance; Crystallographic axes; In-plane fields; Parallel orientation; Perpendicular orientation; Ultra-high; Semiconductor quantum wellsjournal article10.1063/1.49915452-s2.0-85038364808