▁ ▁External ▁links ▁Bug ▁Guide ▁M oth s ▁of ▁Maryland ▁Species ▁info ▁ ▁Category : No ctu inae ▁Category : M oth s ▁of ▁North ▁America <0x0A> </s> ▁E jan ▁may ▁refer ▁to : ▁ ▁Places ▁▁ ▁Ay jan , ▁Mark azi ▁Province , ▁Iran ▁ ▁E jan , ▁Gh ana ▁ ▁People ▁▁ ▁E jan ▁Mack a ay ▁( born ▁ 1 9 4 3 ), ▁Canadian ▁legal ▁scholar <0x0A> </s> ▁In ▁super con duct ivity , ▁the ▁super con duct ing ▁coh er ence ▁length , ▁usually ▁denoted ▁as ▁ ▁( G reek ▁lower case ▁x i ), ▁is ▁the ▁characteristic ▁exponent ▁of ▁the ▁variations ▁of ▁the ▁density ▁of ▁super con duct ing ▁component . ▁▁ ▁The ▁super con duct ing ▁coh er ence ▁length ▁is ▁one ▁of ▁two ▁parameters ▁in ▁the ▁G in zburg – Land au ▁theory ▁of ▁super con duct ivity . ▁It ▁is ▁given ▁by : ▁ ▁where ▁ ▁is ▁a ▁constant ▁in ▁the ▁G in zburg – Land au ▁equation ▁for ▁ ▁with ▁the ▁form ▁. ▁ ▁In ▁Land au ▁mean - field ▁theory , ▁at ▁temper atures ▁T ▁near ▁the ▁super con duct ing ▁critical ▁temperature ▁T c ▁, ▁ ξ ( T ) ▁ <0xE2> <0x88> <0x9D> ▁( 1 - T / T c ) − 1 . ▁Up ▁to ▁a ▁factor ▁ ▁of ▁, ▁it ▁is ▁equivalent ▁▁ ▁characteristic ▁exponent ▁describing ▁a ▁recovery ▁of ▁the ▁order ▁parameter ▁away ▁from ▁a ▁perturb ation ▁in ▁the ▁theory ▁of ▁the ▁second ▁order ▁phase ▁trans itions .