Magnetotransport in the MAX phases and their 2D derivatives: MXenes

Herein, we critically assess magnetotransport in the MAX phases and their 2D derivatives, MXenes. For some MAX phases, a simple, 2D hexagonal metal model describes weak-field magnetotransport of their nearly free electrons reasonably well. For others, experimental and/or theoretical Fermi surfaces need to be mapped-a crucial task required for true understanding. Even less is known about MXenes. The density of apparent mobile carriers in Ti(3)C(2)Tx-assuming a single-band model-is approximate to 1 x 10(14) cm(-2) (1028 cm(-3)), which justifies it being sometimes described as a 2D metal. Much work is needed before a clearer picture emerges. [GRAPHICS] IMPACT STATEMENT Magnetotransport in the MAX phases and their 2D derivatives MXene are critically reviewed for the first time. For some, a 2D hexagonal metal can explain magnetotransport; in others not.