name a place where such dwarfs can be found?
The Sirius binary star.
White dwarf
The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star. 
how does a white dwarf form? After the hydrogen-fusing period of a main-sequence star of low or medium mass ends, such a star will expand to a red giant. It the red giant  has insufficient mass to generate the core temperatures required to fuse carbon it forms a planetary nebula. The remaining core is the white dwarf. what metals does it contain? UNANSWERABLE when was it discovered? In 1910. and who discovered it? Henry Norris Russell, Edward Charles Pickering and Williamina Fleming. mention a few works published by the first person? He co-authored a two-volume textbook titled "Astronomy: A Revision of Young’s Manual of Astronomy" . how is the magnetic field of white dwarf? Since 1970 magnetic fields have been discovered in well over 200 white dwarfs, ranging  0.2 T to 100 kT. is it habitable? It has been proposed that white dwarfs with surface temperatures of less than 10,000 Kelvins could harbor a habitable zone at a distance of c. 0.005 to 0.02 AU. does it have any debris around it? Yes, mainly dust clouds.
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White dwarf [SEP] Introduction
A carbon–oxygen white dwarf that approaches this mass limit, typically by mass transfer from a companion star, may explode as a type Ia supernova via a process known as carbon detonation; SN 1006 is thought to be a famous example.