Motor

1. A motor comprising a steel sheet used as a core material of the motor, wherein

the steel sheet includes a composition including: by mass %, 0.010% or less of C; 2.0% to 7.0% of Si; 2.0% or less of Al; 0.05% to 1.0% of Mn; 0.005% or less of S; 0.005% or less of N; and balance Fe and inevitable impurities;

the steel sheet includes a magnetic flux density changing area where a change ΔB in magnetic flux density to a change ΔH=50 A/m in a magnetic field, is equal to or higher than 0.50 T;

a thickness of the steel sheet is 0.05 mm to 0.20 mm; and

an eddy-current loss of the steel sheet, at 1000 Hz−1.0 T, is equal to or less than 0.55 of a total iron loss, wherein

a difference between a concentration of Si at a surface of the steel sheet and a concentration of Si at a center portion of the steel sheet is 0.5% to 4.0%, and

a saturation magnetic flux density Bs of the steel sheet is equal to or greater than 2.0 T.

2. The motor according to claim 1 , wherein the steel sheet further includes: by mass %, at least one element selected from 0.01% to 0.1% of P; 0.001% to 0.1% of Sn; 0.001% to 0.1% of Sb; and 0.001% to 0.01% of Mo.

3. The motor according to claim 2 , wherein the magnetic flux density changing area is present in an area including a magnetic flux density equal to or higher than 1 T.

4. The motor according to claim 1 , wherein the magnetic flux density changing area is present in an area including a magnetic flux density equal to or higher than 1 T.