php find lowest value in associative array

1$a = [
2	['emp_id' => '1', 'name' => 'ram', 'age' => 40],
3	['emp_id' => '5', 'name' => 'ram_1', 'age' => 20],
4	['emp_id' => '2', 'name' => 'ram_2', 'age' => 30],
5	['emp_id' => '3', 'name' => 'ram_4', 'age' => 25],
6	['emp_id' => '4', 'name' => 'ram_3', 'age' => 50]
7
8];
9// please find minimum age employee in above array.
10
11echo min($newArray);