movz
The ARM64 instruction that puts a 16-bit number into one quarter of a register and zeros the rest.
movz xd, #imm16, lsl #s (s = 0, 16, 32 or 48) writes imm16 << s to xd and clears every other bit; it starts a movz/movk sequence for a wide constant.
Examples
movz x0, #0x1234, lsl #16setsx0to0x12340000, clearing every other bit.