Fig. 4: Tunable exciton spin orders with magnetic field and exciton filling.
From: Tunable exciton valley-pseudospin orders in moiré superlattices
a, b Magnetic field dependence of PL raw helicity ηPL (a) and GH (b) at νex = 1.1 from 0 to 30 mT. The GH transforms from a “Λ” shape to a “V” shape and saturates at ~20 mT, suggesting a phase transition. At high field, GH exceeds 1 in a wide range of pump helicity, indicating spontaneous increase of spin polarization, which is the hallmark of an FM-z spin order. c, d Same as (a, b) for νex = 1.3. The zero field GH is similar to the high field GH at νex = 1.1, signifying an FM-z spin order at zero field. The “V” shape GH is further enhanced by Bz. Data are shown as lines and symbols for Bz = 0 and 30 mT; and only lines are shown at other magnetic fields for visual clarity. Error bars represent standard deviation in PL helicity and GH. Error bars in (a–c) are smaller than the symbol size.
