[1] Kannur Univ, Sch Pure & Appl Phys, Payyanur Campus, Kannur 670327, Kerala, India
[2] Kannur Univ, Dept Nanosci & Nanotechnol, Payyanur Campus, Kannur 670327, Kerala, India
[3] Kannur Univ, Nirmalagiri Coll, Dept Phys, Kannur 670701, Kerala, India