其中条件db数组包含值Laravel Mongodb

i have document like this

{
"_id" : ObjectId("512e28984815cbfcb21646a7"),
"primary" : [
    "0":{
         'abc',
         'xyz'
         }
        ]
 },
 {
"_id" : ObjectId("512e2898481asdf7asdf7"),
"primary" : [
    "0":{
         'xyz',
         'ght',
         'aaa'
         }
        ]
 }

here i want to get all records that contain 'xyz' in primary.0 array

also tried laravel whereIn and aggregate $in but no luck..

please suggest me solution in laravel or mongodb aggregate..