  Since the discovery of graphene, two-dimensional materials with atomic level
thickness have rapidly grown to be a prosperous field of physical science with
interdisciplinary interests, for their fascinating properties and broad
applications. Very recently, the experimental observation of ferromagnetism in
Cr$_2$Ge$_2$Te$_6$ bilayer and CrI$_3$ monolayer opened a door to pursuit
long-absent intrinsic magnetic orders in two-dimensional materials. Meanwhile,
the ferroelectricity was also experimentally found in SnTe monolayer and
CuInP$_2$S$_6$ few layers. The emergence of these ferroic orders in the
two-dimensional limit not only brings new challenges to our physical knowledge,
but also provides more functionalities for potential applications. Among
various two-dimensional ferroic ordered materials, transition/rare-earth metal
halides and their derivants are very common. In this Research Update, based on
transition/rare-earth metal halides, the physics of various ferroic orders in
two-dimensional will be illustrated. The potential applications based on their
magnetic and polar properties will also be discussed.
